Poping noise starting up Mcintosh MA 6900

I went to McMasters training, and have a working acquaintence with the products.
Popping through your speakers is not good. The pre amp could have some bad capacitors. The issue here is that if something goes, you could conceivably pass dc, that is direct current, destroying your speakers.
Call McIntosh directly, and get their service department on the line. In the meantime, if you bought it from a local dealer, and it is relatively new, ask him for a brand new one to replace it. McIntosh is really, really, good about this kind of customer service.
Good luck,
Oops, another thought, though a little obtuse. could the popping be coming from noise in the line, and simply coincidental to turn on. (Refrigerators coming on etc send jolts through the line, and I have actually seen this blow tweeters) But that is not the issue since, it only happens on turn on. Just a random thought.
Larry

Sorry,
I did not know that the 6900 could not pass dc.
Also, what kind of ground loop could cause a popping noise.
60cycle and harmonics of, but popping I have not experienced.

The reason I suggested exchanging for a new one, was that I did know that McIntosh would back the dealer on the replacement. That is where they excell.
Glad you are now getting what you deserve, an amp which does not pop.
On the passing dc thing, I know that the gentleman could be correct, but I am always one to suspect the worst when it comes to something like this.
I have had McIntosh amps take out drivers before, so not passing dc must be new to their design. It has been several years since I attended McMasters. Maybe there were mitigating circumstances in my experiences. Anyway you are well served.
Good listening.
Larry