Any difference in SQ from USB drive storage to NAS playback?

As long as there is enough bandwidth to transfer the data fast enough ( there should be with most home network connections or with most any properly functioning  usb drive with cd resolution files ) there  should  be no difference. 

If not, some streaming software is designed  to be able to reduce streaming resolution accordingly,  but in most cases the music will simply stop playing while the data rebuffers up enough  to stream again at the source resolution.  

Behavior here could vary streamer  to streamer.   

Otherwise, there should be no difference.   The storage device is either capable of delivering the data fast enough or not.  

I can't  see USB2 being a bottleneck for music. The average uncompressed music file is about 50- 60 MB, a CD is around 680 - 740 MBs, USB2 runs at 60MBs a second so if everything could process it, theoretically you could play an uncompressed song in 1 second over USB2.

Usb 2 bandwidth is ~480 million bits per second.

Cd resolution music bitrate is 1.4 million bits per second.

No problem. Not even close. 

For Melco (and I believe for Innous as well) a good part of the game is jitter reduction. There is both an ethernet line in as well as an ethernet player port out. Everything gets reclocked by the Melco. So in effect devices such as the Melco function as an ethernet line conditioner.