Hey guys. I recently ordered the ibasso P2. (http://www.ibasso.com/ShowProduct.aspx?ID=37) The device works great, although I've got one rather major issue with it. One reason I bought the P2 was because it came with the AC adapter to plug it into the wall. I don't want to use it as a portable device, and just want it to sit at my computer. Hooked up to my PC's sound card is a set of Logitech Z5500 speakers. These have a headphone port on the control center. I simply plug the P2 into that headphone port, plug the AC into the wall, and then plug my headphones into the P2. Seems like it should work and be great. Cuts power to the speakers, sends it to the headphones, and this works. The catch here is something I never knew about; ground loop. Apparently, because the speakers/computer/P2 are all plugged into the same power grounding, it creates some crazy electrical loop and this loop creates something called mains hum. This hum/buzz can be heard clearly in my headphones when using this setup. To solve this, unplug the AC adapter to the P2, and boom, gone. Now, this in turn means, it works fine with portable devices, like you'd think. iPod, PSP, DS, they all work fine without this issue. But I bought this for my desktop. Yes, sure, I could just charge it, use it, and then charge it again, but I did not pay $157 for an amp to have an inconvenience like that. I want to plug it into the wall, and not have to worry about that. Not to mention charging it like that all the time wears out the battery so it won't be any good for when I do want to use it portably. So, in the end, I am looking for a fix. I know I can buy some $80-100 power strips that create their own ground. Don't want to spend that much. Yes, I know there are devices like the following: PAC SNI-1/3.5 Noise Filter Helps eliminate ground loop noise from your portable music player! (3.5mm plugs) at Crutchfield.com Although, I fear that could alter sound quality, and again is nearly $30 shipped. I figure that you guys, with all your experience with this stuff have found ways to solve this. Any way to power the amp over USB? (It is a 12V DC Adapter) Thank you to anyone that can provide some incite. Various Info: - P2 uses a built-in 8.4V 470mAh Li-polymer Batteries or external power - External power supply: 12V DC - Battery Life: 11 hours - Battery Charge time: 3 hours - Both the Z5500 and the Headphone amp use a two-prong power adapter, so there are no grounding rods involved - The same thing happens when I plug my P2 directly into my computer, maybe it is the original source of the buzz/hum?