Thanks for the information. The cabling is as follows:

- new M5 lead (from Ian Fraser) from 568 to left DSP33 inputs (switch set to left)
- new S5 lead (also from Ian) from left DSP33 comms and digital outputs to right DSP33 inputs (switch set to right)
- C5 lead from 568 to HD421 (this works fine when source on 568 switched)

The DSP33s are stuck at some intermediate volume (approx 50). Oddly, they seemed to respond to volume changes a couple of weeks back. The problem appeared first as a sort of "stepped" response, where the volume would jump after the volume was increased or decreased by 10 or more steps. It worsened such that response would be even more intermittent, requiring larger and larger volume moves on the 568 to get any change on the DSPs. The analog surrounds and sub always responded normally. Now, the DSPs don't respond at all to volume changes and remain at 50 or so. They sound great, by the way!

Sincere thanks,
Roger