USB stick – is it really possible to achieve a superior sound quality when streaming off it?

I have a Pioneer N50 for the moment, and I'm happy with it. Has anyone else experienced as I do a difference in SQ with exactly the same material when played over (wired) the network compared to USB stick? Material that is copied onto the USB (front input) sounds markedly better, more 'fluid', with better soundstaging.

Pity I can' t copy all material from my NAS to USB-sticks. I didn't dare to attach a small HD to the USB input. Probably wouldn't work. But something seems to get lost on the way in the NAS-network-streamer chain.

http://www.pinkfishmedia.net/forum/showthread.php?t=160239