True that DVI doesn't carry audio, but if everything was hooked up the way he said (and nothing else) then he wouldn't have audio for cable or dvds (which I assume he's playing in bdplayer) either.
So he either means HDMI but said DVI, or perhaps he's using HDMI for BD & Cable to AVR but actually using DVI from TV to AVR.
Assuming he's actually using HDMI (not DVI). then something is not working as it should. If it were me, I'd first check to make sure it wasn't a servio problem, If the TV itself can play files thru USB, I'd put one of the files on usb flash stick or drive and then make sure sound is good that way. If not, figure out why - is it something with file, does tv not support that audio format, is wrong cable used, etc. I've heard some TVs only put out stereo on HDMI when passing audio from external source... dunno if network counts as external source tho, but even if that was the case you'd still get stereo sound.... so yeah if sound when playing straight on tv, then I'd try another DLNA server software on the pc... even samsungs software as a test, since it's free...
Also, does the BD player support DLNA also? If so, that might be an alternative, since it's on the network and sound is working from it.
Samsung F8500 | Tivo Roamio OTA | Yamaha RX-A1040 | Oppo BDP-103