[Richard]

I think this applies to a few years. There are several reasons you may need to remove the speaker panels located above the driver and passenger. Mine were rattling when driving so they needed some felt in the touch points. You may have to replace or repair a speaker, or if your speakers start to buzz and crackle the relays that switch between the house stereo and the dash stereo are located behind there on some coaches. 

These panels are not intuitive to remove.

There are two screws underneath hidden by the curtains. Remove both.     
Then remove the door that swings upward. Otherwise you won’t have enough swing to get the panel out. 
Then pull outward about 3/4 inch on the bottom of the panel. Then push/pull/tap the panel downward. Yeah, I know, the instinct is to push up. 

Here is the backside of the panel, and the mounting cleat. So you can see why you have to pull down. 
       
And a pic of the relays and speaker crossovers behind the panel. I do not know what the relay on the far right does. It switches 120VAC. And mine hums, so a new relay is on the way.
   

[pairodice]

I had one of those A/D/S (analog/digital/something???) boxes under the dinette behind the drawer where our vacuum cleaner is located. I wonder if that is for the speaker in the rear of the salon slideout? Is that an amp?

[Wanderman]

How big is the box? Could be the subwoofer.

[Richard]

No, its the crossover the divides mid freq from high freq to the woofer and tweeter. You will have one for each set of speakers

[pairodice]

Richard, that makes complete sense that those are crossovers - not sure why they ran the rear speaker crossover way down on the floor under the dinette but maybe there was no other decent place to put it. I don’t think we have a subwoofer anywhere (none that I can hear). I may end up adding one so the TV sounds better - my previous coach I added a sub under the couch and it made for great theatre sound.

[Richard]

As you know from disassembling the salon ceiling, putting the crossover for that speaker in that space would have been very tight.