I have the Hifiman HE6 headphones and Schiit Lyr amp hooked into a Behringer USB DAC playing music from my (mainly) FLAC library. In theory, what should I set the volume on my computer to? Is there any real-world difference?
Yup, full digital volume. Although that should still allow the volume pot to go up to at least right before 9:00 on the dial. My Superpro DAC gets 5v for the DAC chip and receiver chips when fed a signal through USB and the opamps get the PSU, so that way the signal is too loud, I had to turn down the digital volume to 25% on Windows. Although it did sound better controlled; probably due to the extra power.
If you are running an older Win system (say XP) upgrade to Win7...the audio layer in MS's latest O/S is vastly superior to XP. The latest Win7 SP (SP1) has reworked the USB driver for greater SQ if you use USB. As for the vol level on the comp...as the others have said keep it at 100%...lowering the volume digitally cuts resolution (bit depth is shaved) and degrades the signal quality. The Behringer DAC is your weakest link in your system next to the O/S if it's XP. I'd look at a used HQ dac next and if you are using XP O/S think about upgrading to Win7. Source quality once optimized will bring yet another level of performance to your ears .....depending upon what source you choose that SQ improvement could be anywhere from small to huge. You have a great amp and cans...get the source up to snuff and you'll be set for a long time to come.
I just setup Foobar to use ASIO output and bypass the windows mixer.
I'm considering buying a better DAC. But honestly I have a hard time believing it's going to make any noticable difference. Not to mention that I've already spent way too much money as it is. Seeing as I'm in college and college interns don't really make all that much. Haha