Volume setting question

[Napalm Frog]

Okay, I didn't notice this until today, but my music sounds different depending on the volume I have my devices set at. There is my PC (Foobar via WASAPI), Fubar III, then M-Audio AV40 (I have the headphone amp in the middle because I use my headphones a lot).

Obviously, when I make either the Fubar or the AV40 the music goes louder. However, the ratio of volumes produces differences in the low end (I'm a bassist and I can notice it immediately... for all I know, there is difference in the highs as well). When the AV40 is high and the Fubar low, it sounds normal: tight, punchy bass. When the Fubar is high and the AV40 is low, the low end sounds "fuller". Not muddy or anything, just more rounded (if that makes sense).

I assume this would be normal, I just need to tweak to get the right sound that I want. Is there any advice you can give me regarding this? Or should I just connect the AV40 to on-board sound, and the headphones via the amp, despite the audio out on it?

 

[ashmedai]

I just assumed it was PC --> Fubar III --> AV40 because the Fubar III is a USB DAC with line-level outputs, and that it had nothing to do with headphone usage frequency.

Typically, you don't want the volume knob of your headphone amplifier to affect any preouts. Unfortunately, it sounds like it does. What's happening is that for a given volume, you're adjusting which amp is doing how much of the work, with a corresponding weight given to the dominant amp's coloration. This is already a pretty non-ideal situation, but that's how the Fubar is wired. I'd just adjust it to match your preference.

You could use the onboard sound as a reference, but it's hard to imagine it doing better than the Fubar.

 

[obobski]

I just assumed it was PC --> Fubar III --> AV40 because the Fubar III is a USB DAC with line-level outputs, and that it had nothing to do with headphone usage frequency.

Typically, you don't want the volume knob of your headphone amplifier to affect any preouts. Unfortunately, it sounds like it does. What's happening is that for a given volume, you're adjusting which amp is doing how much of the work, with a corresponding weight given to the dominant amp's coloration. This is already a pretty non-ideal situation, but that's how the Fubar is wired. I'd just adjust it to match your preference.

You could use the onboard sound as a reference, but it's hard to imagine it doing better than the Fubar.

yeah, it should be line level out
but the fubar isn't driving the AV40's, don't be mistaken there, its adjusting its level output, as you get the signal closer to line level (2Vrms) the AV40's perform better because the amp isn't having to compensate

basically I would hook the AV40's up to onboard and set that to 100%, as you'll get line there, or see if theres a setting on the Fubar that switches its output from variable to fixed

just another Q:
what settings is your PC's output volume at?

 

[Napalm Frog]

Well, because of WASAPI output, I need the PC volume at 100%, and Foobar is set at anywhere between 50-75%. As for switches, there is only one for high/low gain, meant for higher impedance headphones.

 

[ashmedai]

as you get the signal closer to line level (2Vrms) the AV40's perform better because the amp isn't having to compensate

Yeah well, unless he has an RMS AC voltmeter in his back pocket, we can pretty much chalk it up to bad design and say play it by ear. Unless you can think of a better workaround, or know someone that's analyzed the thing to find out?