[LAU] bit-transparent playback/recoding over AES using an RME 9632 card

Hi, I try to get bit-transparent playback/recording of a stereo stream with a RME 9632 card. My test setup the card clocked at 48 kHz and the AES input and output looped. When I tried to use pure alsa, I recorded 10 channels to get channels 9 and 10  which is the AES input (I wasn't able to find a way to record only channels 9 and 10). However, I'm not able to play back anything during the recording. I get the error message "set_params:1361: Unable to install hw params". I also tried jack and started jackd this way: $ jackd -R -d alsa -d hw:DSP -z none -M -H I was able to play back a square sample and record channels 9 and 10 using jack_rec. However, the result looks like it went though bad AD/DA conversion: jumpy edges and the linear parts unclean, too. I'll try to find out if the playback or recording part is the culprit. However, I'd like to get some comments if bit-transparent playback/recording can work at all with my setup. If it does, I'd appreciate to get some hints how to achieve this. Regards, Tino