There were actually two issues here. One is a bug in Roon–this is what causes the stuttering sound, and it will be fixed in our next release. Thanks for the report!
The other problem relates to the way these filters are defined. Roon is seeing a convolution config that goes from 2.0 -> 4.0.
In other words, the output of the filter is being interpreted as 4.0 data: Left,Right,Center,Rear-Center. And then that is being mapped onto the 7.1 layout configured at the audio device, which actually doesn’t have a Rear-Center channel, so you end up losing one of the subwoofer channels in the final mapping.
Instead of getting 4.0 involved, I suggest a slight alteration to your
.cfg files so that they produce 7.1 in the same order as the connections on the back of the device. This will disable the channel mapping entirely. Then inside of the .cfg, you can treat the layout as a flat list of 8 channels. Roon is “smart” about not sending empty channels over the network or spending effort processing them, so this change should not produce extra cost/work in the system.
At the top of each of the config files, try changing this:
44100 2 4 0
0 0 0 0
44100 2 8 0
0 0 0 0 0 0 0 0
There are 2 changes in each file: a 4 is changed into an 8 on the first line, and on the third line, add four extra zeroes. The remainder of the file remains as-is, as do the .wav files.