Hi,
I'm trying to get DD/AC3 *properly* working with vdr and my reciever a Marantz SR5600.
I'm using the VDR with the current Firmware (F22623) for my FF ttpci-dvb card. The SPDIF-Signal comes from J2 and goes to a Marantz SR6300. All Dolby material (DTS/DD/AC3) i've found yet works flawlessly (only small problem is the slow switch of the receiver when the signal) in VDR, mplayer[-plugin] and dvd[-switch]-plugin. So, have you tested the most current driver and firmware for your FF card?
current FW: http://www.suse.de/~werner/test_av-f22623.tar.bz2
Does using the bitstreamout plugin help in any way?
I never testet bitstreamout, but i guess it might improve your situation (depending on your soundcard).
best regards, Alex :)