After rereading the above posts and also the June 3rd thread started by Bri1270, it appears that the pop heard on acquiring or reacquiring a DD signal is probably unrelated to the DD source.

In my case, the pop in the rear speakers is quite noticeable at the instant my DISH 622 satellite receiver or Denon 1920 DVD player first receives a DD signal. And it always happens when resuming play from a pause on the DISH 622 DVR. It only happens when the Denon DVD player first sees a DD signal; i.e. it doesn’t pop when resuming play after pausing with this unit. It would seem that the DISH 622 receiver loses the DD signal during a pause and the Denon DVD player does not.

I did not hear this pop with the 990, using Outlaw balanced interconnects, when running DD 5.1. It first appeared on the rear speakers after adding a 2-channel Adcom amp, via unbalanced interconnects, to enable DD 7.1 playback.

There has been a significant amount of very good troubleshooting performed by Daryl, Jester7677 and Bri1270, and others. And, as usual, there has also been excellent input from gonk. But the popping sure seems to be directly related to some 990’s acquiring a DD signal from any source.

I really don’t like the popping from the rear speakers, but the 990 is such an excellent pre / pro otherwise, I will live with it. Hopefully, a future firmware upgrade will eliminate this one irritating condition.

By the way, for those that are experiencing this popping noise through your speakers, are you hearing it on all five channels on DD 5.1 and all seven channels on DD 7.1 (if running that configuration)?

Thanks!