great... Looking forward to your findings...
Here is what I found, after a lot of changing sources and playing a same piece of music...
Song selected - Ishq Bina from Taal
I selected this single FLAC and same converted to MP3 V0 and played the same song through all the available options of digital playability, namely:
1. Network wired DLNA (Direct from AVR)
2. Network WiFi DLNA (From AVR)
3. Android WiFi DLNA
4. Bluetooth streaming thru Android
5. AVR connected to PC (Foobar) & HTPC (XBMC) via HDMI
6. USB in AVR
1-3 - sounded almost the same.
4 - sounded a little less rich, I guess due to Bluetooth limitation of bandwidth
6 - sounded similar, but I felt 1-3 being better as it was more rich.
5 - was the best. I dont know why, but playing music thru foobar with wasapi drivers sounded very much open and rich compared to all. Similar goes with HDMI connection with HTPC and playing thru XBMC.
FLAC's sounded more rich and full whereas, MP3's were less. Once you here FLAC's you do not want to go to MP3's. That's my opinion.
In all the above options the least preferred is the USB as "elangoas" stated. But in general if I talk in percentage basis playing thru USB was somewhere around 7-10% degraded, compared to all.
@elangoas, it was fun doing this, thanks for opening up this discussion.