Originally Posted by M-13
I've done some personal experiments and for the life of me can't hear any difference whether I'm playing off a external hard-drive or the internal SSD of my laptop. The audiophile in me prefers playing directly from my laptop SSD as there is one less wire my music goes through, but then I wonder because I can't hear any audible differences, at least from my laptop and my external hard drive. I think it's easy enough to experiment. Duplicate the file and try A/B back and forth to see if you can hear any difference.
Ever since installing my Ciunas my music enjoyment has taken a huge step forward. But something was missing. I still wasn't getting that nice, creamy vinyl sound. Being I had very little frame of reference, and it's so hard to A/B this stuff, I figured: it is what it is.
To add to the confusion I've moved my entire library around a few times and I thought the degradation I was experiencing might be due to this.
Being that I store AIFF files, my 1TB USB drive was getting full anyway, so I pulled the trigger on a 3TB Firewire 800 drive. Since USB 3.0, Firewire has dropped in price-if you can even find them.
Well...problem solved! I've been working my way through my library and even crappy little MP3 files sound much better. Before everything sounded 'efforted', with little bits of occasional break-ups. Now, if I closed my eyes and pretend, I could swear a slab of vinyl was spinning in the corner. The only thing that brings me back to digital reality is the lacks of pops and crackles.
So yes, I would conclude that it is bad to retrieve music data through a USB port while simultaneously playing back through a USB DAC.