I recommend the movie "Scream."

Just kidding, Jason J has a good point and it would be interesting to try different demos and see if one or two movies are the culprits.

I recall in my retail days, a customer thought they had either a bad speaker or a bad CD. So they brought the CD to the store and we played it on our reference system (the CD was "Nojima Plays Liszt"). Turns out the equipment was not defective, but instead, so revealing of the source material, you could hear where the mic picked up the impact sounds of Nojima's finger nails striking the keys.

Lastly, regarding the pop, it's not unusual to hear a power-on noise if the preamp is turned on or off when the amp is on. Case in point, my amps and electronics are plugged into two Adcom ACE-515 AC enhancers that delay powering-up the amp sockets after the "accessories" sockets to prevent turn on thump. They cycle off in reverse order.

Next time I think about it, I'll try powering the 970 on and off with the amps on to see if I can duplicate the noise you're getting.