Headphone AMP, Asio and Foobar

[IamKirk]

I recently picked up an IBasso D2 Boa for my Sennheiser HD555. I had heard that they can improve things substantially, from headphone.com review of the 555's. Great sound so far. I got asio going and the usb going on IBasso. My only complaint is that i can sometimes hear a hiss in the background. Asio improved things substantially though. I am just assuming this is from poor recording/vinyl transfers, etc. I have like 5 things plugged into the USB slots on the back of the computer. I have a DFI Lanparty Nf 250 motherboard (I think those are the right numbers...). Are there any tweaks/changes I should be making to my setup on the software/hardware end? I keep feeling like the usb situation may have something to do with it, but i can't unplug a lot of the devices and still play music. Keyboard/mouse/external HD, dac/amp Ibasso. What kind of settings should asio4all offline settings have for this 16bit/44.1 dac. I followed some guide i found on hydrogen audio. 2048 buffer size, latency compensation at 0 in/out. Kernel Buffers at 4, then unchecked the resample and force wdm. I got my stereo setup to where I wanted it, so I just wanted to get this setup to the best possible point given my current hardware/limited money lol.