Have a client with a Crestron DM/ Sonnex system we put in a few months ago. Client decided to add a second surround zone into the mix.

Put a Marantz SR5008 and a Triad speaker bar and triad sub in place, rerouted the existing in wall speakers to act as rears, ran digital audio output from SWAMP to the AVR, changed programming and called it a day.

Fast forward a couple of months. Client contacts me saying he is having audio drop out issues. Went out and looked at it, couldn't replicate problem.

What is happening according to the client is after 15 minutes to 6 hours of that zone being in use, the audio drops out in the surround zone. It ramps down, like someone pressed and held the volume down button on the AVR. Audio remains gone until the volume up button is pressed (either on the MLX3 or their Ipad), volume then returns at the level that it was before it dropped out. They don't have to issue multiple commands, a single volume up command restores it.

I had the client check, when the audio goes away, the volume display on the doesn't change, nor does it show as being muted. No amplifier relay click is heard during this process either. AVR is being controlled via IP for what that is worth.

Where it gets somewhat more complicated is that the AVR is essentially being fed 2 channel audio from each source as the client elected to not have us pull digital audio from each source, feed it to the SWAMP and send it to the AVR. Nor could we use extenders to send HDMI to the AVR from the DM output and feed it to the display from there (logistically would have been a huge challenge). Client was unconcerned about "true surround sound" at this location, he has a theater for movie watching, just wanted more/better front of the room audio presence.

Audio pathway is HDMI out from source equipment to DM, Analog out from DM to SWAMP, Digital out from SWAMP to digital in on AVR. Video is wrangled from DM directly to display.

I really don't want to go throwing parts at this thing, especially since I have not seen the problem in person. Hopefully somebody has seen something similar and can point me in a general direction. It is a huge challenge to schedule the client, our programmer and myself to be on site at the same time, much less having to sit around all day and watch tv waiting for the issue to manifest itself.

We have this setup in several projects and have not seen this issue. I can say we do the audio connections straight from the sources and not loop outs via DM dsp cards.

So I would assume the issue lies in the DM. I honestly didn't read every word but I wonder if it is specific to a certain source material like DD.

DM cards DPS or not DPS?

Does this drop out happen when another zone is turned on or turned off?

You are running Audio for that zone from BOTH the SWAMP & the DM?

You SURE it is ramping and not just going out?

When it goes out can you have them select the built in tuner on the Marantz, still have no audio or does audio come back?

If you mean DSP, then yes.

No. I asked them if any other zones were in use when this problem occurs.

No, audio is from SWAMP, video is DM.

Per the client, it is ramping. I pressed and held the volume down button on the remote while I was talking to them, they said it sounded exactly like that.

Good idea.

The part that is leading me towards the AVR being the issue is the SWAMP is not being used to control volume. I can see no way that changing the volume level on the AVR would have any impact on the backend of the system. Since a volume up command (or volume down for that matter) restores audio, I am leaning towards the AVR.
Just want get second opinions before I go through the trouble of getting a replacement. Just in the odd chance I am missing something.
Plus, they (5008s) are on back order.

Yeah marantz is out of control with these back orders right now. I wonder if you can test with direct analog outputs from the devices that are capable as well as add a quick programming step to "tap" the volume + then -.

Have you used Debugger to see what command if any is being issued when this happens?