Thanks Jester, I guess I'll save myself the trouble then.

I have heard this as well, and also have the H20 Receiver. Perhaps it's the receiver?...

H20, as in DirectTV reciever?

I don't have one, but if I have just one component connected to the 990, it still does it.

Take your pick, they will all result in the same conclusion:

SA 8300HD
XBOX 360
Denon 3910

Again, to test you need a signal, and to get a signal, you need at least on component connected... All of the above are connected via TOSLINK only.

Even disconnected the cable from the 990 to the TV (to see the setup menu), and no change.

If it is a ground loop caused by product, I've just about eliminated all hum using the common ground (no cheater plugs).

Whatever it is, I wish it was either more common, or more forgiving. Other than that, the 990 works out well for me using the balanced connections.

Just wanted to give an update on my popping issue. It's gone !! I had been using two amps and recently moved everything to one amp. I had been using an Aragon 4004mkII for the front and an Acurus A125X5 for the center and side ssurrounds. I thought I would try connecting eveything through the Acurus since I only noticed the popping in the front channels. Since then, no popping. It seems that there is probably a ground loop issue between the two amps. Hard to figure since they both connect directly to the same power conditioner. I haven't yet tried using a "cheater" plug on the Aragon and re-connecting it to the front channels. By the way, all cables are unbalanced.

good work getting the popping sound solved.. who would have thought it was the use of two amps? Thanks for posting your findings..

I still have this problem.

I have a Monster 3250 powering the fronts/center and an Onkyo 100X2 (don't have the model name off the top of my head) powering the rear.

Pop only comes from the fronts/center...

Edit - all electronics are plugged into a Monster Power Conditioner. There is a 'grounding bar' on the amp (might be on the conditioner...), but I'm not familiar with using this.

i've heard that sometimes if an amp comes on after the pre amp. it may give a popping sound... some people use a delay to avoid this happening.

funny, but not all systems have an issue with this. I've never had any issue of amps popping. For some reason it appears the Marantz MA500 amps i use have some kind of 2 or 3 second delay before they kick on. and i don't get any kind of popping at all.

The popping sound we're talking about (at least the one I'm referring to) occurs when the 990 'loses' or 'picks up' a signal. For instance, if I'm watching Cable and I channel up a few times, I will generally hear a pop each time the audio from the new channel is picked up. I noticed the same behavior when using components other than the cable box.

It's not terrible, but enough to be annoying...

I used to have the pop when changing channels. Fixed it by replacing the balanced audio cables, between the 990 and 7500, with un-balanced.

Cost me $140 worth of balanced cables to find out that a balanced connection between the 990 and 7500 creates this poping noise. Outlaw should have told me this before I wasted so much $$.

kgt is your cable box audio going right into the 990 pre? what kind of box is it? how do you have it hooked up?