Understanding DAC vs AMP vs sound card??

E

Eocene

Limp Gawd
Joined
Nov 21, 2004
Messages
446
So I'm a bit new to this entire "high end" audio stuff.... and I'm having a hard time understanding the different components.


I recently upgraded from basic $20 Sony headphones to DT 770 Pro (250 ohm version).. and the difference is pretty clear.


The thing is now I'm looking to add an AMP since I've read everywhere such headphones really benefit from this.... the problem comes when people start talking about DAC and DAC/AMP combos... other people say you don't need a DAC if your mobo supports Coaxial out?

So, I'm looking to spend $200ish ...


Here is my mobo, it seems to support coaxial.. not sure if i need extra cables, etc...

http://www.newegg.com/Product/Product.aspx?Item=N82E16813131232

NOTE: when I go to the Realtek HD Audio Manager on my computer I can't really tell the difference between stereo and 5.1, 7.1 (at least clicking the little speakers doesn't activate any sound except for the two main speakers).


Thanks a lot!


-------
EDIT: I listen to more hip hop type of music... hence the DT 770's (more bass)... also play games/movies, etc
 
Nope, you got some bad info

Coax / TOSLINK (that weird shape with the red light in it) are both digital outputs.

DAC = digital to analog converter

Crash course:
- audio files (mp3, wav, flac, etc...) are digital (0's and 1's)
- file goes to a DAC to become an analog waveform
- waveform goes to an Amplifier to gain power
- amped waveform goes to speakers / headphones and magnets turn that waveform into sound

* Amp's are needed for higher-end headphones that offer a lot of resistence

Now then, motherboards with digital (coax / optical) outputs are nice because they'll send that digital data unmolested to an external receiver. Onboard audio such as the 889 chipsets (realtek I want to say?) are decent. If you're running speakers or headphones, anything 'computer audio' branded or under $100, and the onboard audio will likely be fine.

If you want better, Auzentech X-Fi Forte & Asus Xonar Essence STX both have fantastic DAC & Amp combos onboard and (especially the STX) will be as good as any sub $300 external DAC & Amp you will find.

Personally I run the Beyer 770's also and love them. Went from Reaktek HD 889 to Razer AC-1 to Xonar STX and the Xonar is utterly amazing. If you only plan to use headphones and 2.0 stereo speakers it's the next best $200 you can spend on PC audio. If you game a lot & want 5.1 or greater, get the Auzentech Forte card though, more gamer focused.

if you want waaaaaaay more info, I did a huge-ass writeup a while back
http://hardforum.com/showthread.php?t=1410367
 
Most desktop amps need to fed through a DAC so your best option atm is a DAC with a decent headphone amp. Consider the Beresford TC7250 ($280) and then when your funds persist look into a dedicated headphone amp. That particular DAC does come with a 30 day trial period so if you are unhappy with it for any reason just send it back.
 
DAC Info

Headphone Amp Info

A DAC is used to bypass your sound card's analog circuitry. Typically internal sound cards especially ones built into the mobo can exhibit noise due to the environment, sub par components or both. The DAC takes a digital stream from your computer and converts it to analog. that analog signal is fed into the headphone amp. The headphone amp will drive headphoned with a high resistance such as your DT 770's. This is a rather basic explanation so someone else might be able to spell it out a little better.


Edit: I guess a couple people beat me to it.
 
Thanks for the info guys...


I'm still a bit confused though.


I do have some really cheap 5.1 speakers that I haven't really used after I got the headphones.. though it would be nice to have the option for both things.

I understood that a DAC was needed to convert the digital signal to analog.


If I'm understanding correctly... a better sound card or something like the Beresford (why is it also labeled as an amp?) would give me clearer audio, without distortion?

An amp on the other hand would give me louder and clearer audio?


I was just going to buy this:
http://www.amazon.com/Music-Hall-OB...1?ie=UTF8&s=electronics&qid=1265355924&sr=1-1

I heard the -OBH-21 is better but also a bit more expensive....


So with my current situation... what would you suggest?


Thanks
 
As an Amazon Associate, HardForum may earn from qualifying purchases.
So a soundcard is a DAC and usually a headphone amp as well. One of the primary jobs of a soundcard is to convert the digital data to analogue. The problem is that the components they use are often cheap. Integrated soundcards in particular are often rather budget especially on the amp part. On low impedance headphones this usually means you hear a hiss, on high impedance headphones they often don't get loud enough.

So you can purchase a new soundcard, one that has better electronics, or you can purchase specialized equipment and move the job off the soundcard. If you get an amp what you are doing is basically presenting the soundcard with an easy to drive line level load, something that takes little voltage or current. The amp then handles all the hard stuff of driving your headphones. It'll get louder. have less hiss (though for your phones hiss probalby isn't an issue) perhaps have better bass and so on.

Now, a DAC just offloads the analogue conversion from the soundcard. Instead of using its own hardware (it has DACs), it sends a digital signal to the DAC, which converts it. The idea being that the DAC you get is better quality, has more linear output, less noise and so on. Also, some internal soundcards aren't well filtered and pick up noise from the computer, which an external DAC won't do.

A DAC/amp combo is just as the name implies both in one box. You send a digital signal from your soundcard to the DAC in the box, which then converts it and sends it to the amp.

As for what you want, well up to you. One option is to just get a soundcard with a better onboard DAC and amp. It isn't as though you have to buy a separate unit. However, there's convenience in having things outside with their own volume control. If you want an amp or amp and DAC is also sort of up to you. The amp is likely to be the more important part since the integrated soundcard probably has a fairly poor amp. It's DAC is probably ok, so you may not notice a huge improvement getting one.

If you want the solution that offers you the least trouble, an external DAC/amp combo is probably what you want. That'll let you control the volume externally, has everything in a single box, and removes any problems the internal card has like noise. It may be unnecessary, it isn't as though internal cards can't be well grounded/filtered, but cheap ones often aren't. So you just bypass all that and there's no problems.
 
Sycraft, thanks for that....

That makes a lot of sense. I'm leaning towards an amp at this moment... but I'm not sure if I'll need anything else...?

Basically I'm looking to make the headphones go louder.... on certain things the audio doesn't seem loud enough. I



Any recommendations?


The other thing I'm not understanding is.... room for upgrade...

If I get an AMP now.. later get a DAC... is that really that much of an upgrade?


I see that there are trade-offs.... one solution = better sound card -> HEADPHONES
another solution = USB -> DAC -> AMP -> HEADPHONES
yet anohtr one is = USB? -> DAC/AMP in one box -> HEADPHONES

I'm also not understanding the entire setup...

if i go for a decent $200 amp... i can just hook it up to what exactly???? (how do i know if the mobo I linked supports it..). Also, will I still be able to use my speakers?


Is the Beresford a DAC/AMP combo?

Thanks again


EDIT: I read the extra info thread.. . I'm a bit worried about the USB solution.. I got the impression that only certain audio will be assigned to that output??
 
Last edited:
If you want mostly headphones, but to have the 5.1 option I would highly recommend the $130 Auzentech X-Fi Forte

If you buy and Amp, you will connect it between the minijack outputs from your motherboard/soundcard and your headphones. It will make the audio signal louder without deforming it. This will not correct inadequacies in the base signal, that's what a better DAC buys you.

USB solutions work just fine, some media players may make you manually select the USB out option but 99% work just fine (inc. all games)

Honestly though, unless you're an audiophile on the side I think the $130 for the Forte will be the best use of your money. It will be a big leap over the onboard audio you've been using and the $200 Amp solutions you mentioned will be marginal upgrades over that at best.

I think the only exception is if you like to blast your music at >80 dB....
 
DACs on high-end sound cards are already very good... sometimes incredibly good considering that you get a signal-routing sound processor with it.

I'd just follow the suggestions to pick a high-end sound card. I haven't looked up the electronics on those cards, but I know some of them have great DAC chips like the CS4398 and PCM1796 - the implementation can't be perfect, but it's often pretty good on the high-end units.

Then if the signal strength is high enough for your headphones, you won't even need an amplifier. Some of these card put out fairly strong signals, and some of them have further amplification built in just for headphones.

I'd take a 2nd look at sound cards...

http://ixbtlabs.com/articles3/multimedia/asus-d2.html - here is an objective review of the older Xonar D2

http://ixbtlabs.com/articles2/creative-emu-1820/index.html - and here is a review of a few EMU (creative branch) cards.... notice the 1820m, which has the same CS4398 DAC found in some other cards.

Hopefully someone has been reviewing the newer cards, and hopefully they have continued to improve. (For instance, I know Auzentech has popularized the trends of shielding (not sure if it works well) and easily replaceable OP-AMPS - which is awesome really)
 
I don't want to quote the posts I had comments on, because I don't want to seem like I'm trying to flame people (I'm really really not); some technical notes just bugged the hell out of me

SO:
a straight DtoA cannot generally touch mp3/WMA/etc
DtoD must be done for this happen, however that is accomplished (a DSP is involved, but there are specifics that do and don't matter depending on implementation); a soundcard's "processor" or your computer's general processor (either way, with the help of software) performs these calculations, to decompress/compute the stored data for a DAC to handle (basically theres a lot of "black boxes" between when you click play on the screen and an analog signal comes out)

a soundcard is *NOT* a DAC or an amplifier, exclusively, it has a DSP (Digital Signal Processor) which allows it to do many other things, in the case of something like X-Fi, it can actually do all of the positional audio from a game, decode movie soundtracks, perform SRC (Sample Rate Conversion) from more or less anything to anything (with better quality than anything I've seen with published #'s (Creative's #'s are -136 dB THD 20-20k for SRC, thats a lower noise floor than any speakers or amplifiers I know of)), and many other tasks; the reason I mention this is because many "audiophile" types (again, this is directed at nobody in this thread) will insist that a soundcard is "just a DAC", and that some sort of external device "offloads all processing", it does not, it simply moves the DtoA stage outside of the computer (sycraft explained all of this in more detail); the general myth today holds that a S/PDIF DtoA or receiver somehow handles "all of the processing of audio" when connected, and therefore makes a soundcard worthless, neither of those devices (regardless of how much DSP horsepower they have) is actually handling the "rendering" of audio (I'll use my monitor analogy: if you have a DVI output graphics card, and a DVI input monitor, does the monitor therefore handle all of the graphics processing? no, you're simply sending the data out digitally, and just like with the monitor example, DVI is not necessarily better than VGA)

amps aren't always required if your device (I use this word generically) can meet or approach IEC standards (which call for a 120 ohm headphone output), the vast majority of multimedia soundcards will handle/meet this just fine, the vast majority of mp3 players will not (for example); again, don't buy the hype - plenty of people are happy to spend (waste?) your money for you (again, NOBODY in this thread has gone there)

for more directed comments at people in the thread:
audiochris gives a good explanation and good links to information
archmage: ixbt still reviews cards, they have published reviews for X-Fi and a few other boards, for some reason they brand their site as both ixbt and Digit-Life though (so it makes finding some of their reviews a bit dodgy)

everyone thats said the DtoA on modern soundcards kick ass (I think the entire thread has - except OP) I agree wholeheartedly, if anyone has a question about this, look at either published manufacturer #'s (I don't want to hear whining about "well we can trust this vendor and not this vendor because I said so", that just defeats the entire system and if you really wanna get that touchy theres nothing rational we can discuss) or published (and non-biased) review #'s (like ixbt) for quality multimedia/prosumer boards compared to some of these $300+ "audiophile" devices, in most cases they're equal or the difference is nearly immeasurable
however plenty of "audio types" will gladly tell you that one device sounds one way and one like another (I've started calling this kind of explanation "this sounds like a strawberry while that sounds like a blueberry", for further understanding of why I object so much to this style of reviewing, read more James Randi)

USB devices are generally limited: they limit you to 16/48 stereo audio in the vast majority of cases, cost a considerable amount for the features they do provide, and if you're buying a USB to headphone amp output device, limit the hell out of you in terms of I/O (the only USB devices that go above/beyond this generalization, that aren't designed for professionals or project studios, are the USB Audigy/X-Fi hardware from Creative, and the very expensive Bose Companion 5 speakers (they offer more features than 16/48 stereo, but cost A LOT and have no inputs; I am not suggesting them, simply providing them as an example)

I agree with everything arkangyl and sycraft have said as well

OP:
my most heartfelt suggestion is, if you're happy with what you have now, stay with it; no reason to spend more if thats the case
if you feel some deficiency exists, for example you want more input/output options or something else, take some of the excellent advice from this thread/board
 
Last edited:
Thank you for that - that was a good run-down of everything, and I agree.

I'm glad you stressed that a Sound Card is MORE than just a DAC.

I also forgot about Digit-Life - thanks. I haven't looked at sound cards for a long time.
 
As I understand it... if I want louder music on the headphones without distortion without going all the way and getting a dedicated AMP... I should get a better sound card?

It seems this card seems to be recommended:
AuzenTech AZT-FORTE X-Fi Forte



The impression I'm getting from this thread is that a $200~ AMP solution would not really be much of a difference from getting that $130 card?
 
Eocene said:
As I understand it... if I want louder music on the headphones without distortion without going all the way and getting a dedicated AMP... I should get a better sound card?

It seems this card seems to be recommended:
AuzenTech AZT-FORTE X-Fi Forte



The impression I'm getting from this thread is that a $200~ AMP solution would not really be much of a difference from getting that $130 card?
Click to expand...

why would you want "louder"? you do want to be able to hear your children/grandchildren talking to you, right? :rolleyes:

an amplifier (it does not need all caps...) doesn't just mean "louder without distortion", there are other factors, and as I said, if you have no issues with your current setup, leave it be; if your goal is to just go deaf, I won't help you get there

as far as a $200 discrete amplifier vs a premium soundcard with some form of headphone amplifier, really depends on the amplifier in question, but probably they'll have very similar specs/features
 
Well, I'm not entirely satisfied with my setup hence why I'm looking to upgrade...

I don't really mean louder... from what I understand that as quality improves you don't need to go as loud...

The amp in question was this on: http://www.audioadvisor.com/prodinfo.asp?number=CKOBH11 , currently I'm only considering the amp because I could take it with me when I go away and can't take my desktoop and use it with my laptop (I know it is not portable in the traditional sense)

Currently I'm leaning more towards this sound card (http://www.newegg.com/Product/Product.aspx?Item=N82E16829156010) ... though it is out of stock.


Thanks again
 
Last edited:
Bah, this is the 3rd write...

If you want a good DAC & AMP combo to port around with you:
http://www.audiophileproducts.com/fubar4se

Also look at the whole Fubar line, good products, almost got them myself but the Xonar was cheaper and I didn't need to move it.



Alright, I wrote a longer answer and it's the 2nd half of this, quicker first half for the ADDers out there...

First of all, your audio system has a few key parts:
- digital signal processor (DSP)
- digital to analog converter (DAC)
- amplifier (AMP)
- cable
- headphones / speakers

They can all make your system great or rubbish, you will always have a weakest link and your system will only ever be able to be as good as that weakest link.

Thus, a $200-300 external Amp on any base soundcard won't mean shit.

With the Beyer 770's (and I say as an owner) I think the Auzentech Forte and Xonar Essnce cards match very well in terms of being on the same level of components across the board.

- The Asus Xonar card is better for music but only does headphones & 2.0 (left & right) stereo audio *
- The Auzentech Forte is better for gaming because it has the X-Fi DSP which adds some extra effects for games, it also supports 7.1 audio for 5.1/7.1 speaker setups

* the Xonar does have a digital output that supports 7.1, but when using this you're only using the Xonar as a DSP and thus might as well just get the much cheaper Xonar DX card


Okay, so amplifiers... there are two components to them:

Boosting the Signal
The basic idea of an amplifier from an engineering standpoint (CompEng here!) is that it boosts the signal (technically it can lower it too, different topic though). So say you have 1 volt and want 5 volts, you can use an amplifier. There are several different circuits that can accomplish this and each have their pros and cons, basically there are cheap circuits that have lower limits (5x gain versus 100x gain) and will distort the signal more easily and there are more expensive options which cater to different needs.

The output signal from a DAC is very low, this is needed because, like all computer parts, you really cannot have high voltages and currents parading around a PCB without massive leaks and distortion. Thus, for signal integrity, power is low (also for power saving, if you ran at full power at all stages PC's would use 100 kW rather than 400 w). Thus you need an amplifier. All PC soundcards have amplifiers, if it has a 1/8" or 1/4" output jack, that output is amplified. So long as you keep the PC volume low (volume slider in windows), this Amp gets used less and can do less/no harm. This is relevant if you want to go Soundcard -> external Amp -> headphones.

Generally the different in Amps in terms of signal boosting is minor, if you buy an external Amp that's worthwhile (re: not cheap) it will go as loud as you could realistically want. SuperAmps are more for driving speakers covering 1000 sq. foot rooms.

Distortion
This is really the big area of audio amplifiers. You do not want distortion. In theory you've paid nicely to have a good DAC in your system, so you have a very nice waveform and you just want to give it some more power so you can hear all those lovely tones in your music. Distortion tends to be mapped logarithmically and is rated via SNR (signal to noise ratio) where the closer to 1, the better. In short: in any electrical signal there is 'signal' (what you want) and 'noise' (basically electrons gone wild), thus to tie it back in: a good soundcard gives you more signal and less noise, a good SNR is near 100 dB, a great one is >120 dB, a bad one is under 90 dB.

math nerds said:
SNR = 20log( Vsignal / Vnoise)
Click to expand...

You pay money for an amplifier that will distort the signal as little as possible. SNR is logarithmic thus as voltage (volume) increase, SNR increases by orders of magnitude. Really all you need to know though is higher SNR = good and that this is what you're paying for in an external amplifier.

There is also THD (total harmonic distortion) which is a measure of distortion among harmonics, it's shown as a percentage and you want as close to 0 as possible, this has gotten much, much better over the years. You'll have have harmonic distortion in your cables and in your headphones / speakers so be mindful of your weakest link because you system can only be that good.
 
lets not start with the cable myths, please sir

and the Essence can't do 7.1 via S/PDIF (nothing can)

as far as "Quality improves you don't need to go as loud" -> what?
you really aren't understanding here, there is not going to be some magical "this is 5 times better than this" or "this is half as good as that" type of comparison, its all fluff - if it plays fine now and doesn't distort/clip/etc, thats the best you're gonna get, period. (and anything claimed to the contrary is someone's opinion based on their perception of the world - there is no objective/factual accuracy there)
 
And Obobski is saying that because the distortion of the amplifier + DAC is minute compared to the distortion of the speakers. If everything is working "ok" - that is, the amplifier is driven well within limits and not clipping (that is, clipping off the peaks of the signal's waveform), then it is true that it's difficult to pinpoint differences in an ABX test between amps of the same topology.

It is possible to point out differences between DACs, but that is often more because of the implementation. Some people don't like certain things in their signal paths, and this can perceptibly affect the sound (no capacitance buffer = lack of bass). You can explore that later, however, as there are often plans for mods available for sound cards and popular audio electronics in general (replacing/removing caps, op-amps, etc).

Furthermore, any form of digital volume control will result in some bit-depth loss. Fortunately, at a 24-bit (144db dynamic range) dithered output, we have almost 48db of digital attenuation headroom on our 16-bit (96db dynamic range) CD content before we see a loss of data. This is why people prefer analog volume control (the good old knob).
 
Last edited:
Archmage said:
And Obobski is saying that because the distortion of the amplifier + DAC is minute compared to the distortion of the speakers. If everything is working "ok" - that is, the amplifier is driven well within limits and not clipping, then it is true that it's difficult to pinpoint differences in an ABX test between amps.

It is possible to point out differences between DACs, but that is often more because of the implementation. Some people don't like certain things in their signal paths, and this can perceptibly affect the sound (no capacitance buffer = lack of bass). You can explore that later, however, as there are often plans for mods available for sound cards and popular audio electronics in general (replacing/removing caps, op-amps, etc).
Click to expand...

I read this as pure fluff, no offense; unless the "signal chain" has some nasty component within it, there won't be an audible issue

and until you can consistently show me undeniable ABX data (as in, 90-100% of your sample population can "pass", not 1-2%) I see no reason to change this recommendation for the sake of appeasing a few audiophiles here and there
 
It is possible to change the sound characteristics of amps and DACs with mods.

Some of these mods can cripple the AMP or DAC, that was all I meant.

For instance: Bass is current-demanding, and there are several ways of inadvertently decreasing the current supply (short of under-driving the output transistors).

For an unmodified commercial product - this has no bearing.

Edit: That 1st paragraph of mine was stating that it's difficult to differentiate between amps... I'm not sure how that is "fluff." - it must have been that lack of bass comment. I wrote that in the wrong context now that I look at it again. Still...what I wrote in this post applies.
 
Archmage said:
It is possible to change the sound characteristics of amps and DACs with mods.

Some of these mods can cripple the AMP or DAC, that was all I meant.

For instance: Bass is current-demanding, and there are several ways of inadvertently decreasing the current supply (short of under-driving the output transistors).

For an unmodified commercial product - this has no bearing.

Edit: That 1st paragraph of mine was stating that it's difficult to differentiate between amps... I'm not sure how that is "fluff." - it must have been that lack of bass comment. I wrote that in the wrong context now that I look at it again. Still...what I wrote in this post applies.
Click to expand...

ok in context of this post, I agree with what you've said
I was thinking you were trying to segue into "some amps sound like this and some amps like that and we need to get finicky about their guts" - that is not the case
 
You must log in or register to reply here.
Back
Top