I've had something happen recently that sort of suggests that the IPR3K may be very sensitive to low voltage.
I've been using the IPR3K in a variety of gigging settings since the spring. I've used it parallel mono or bridged. And I've also used it for every rehearsal I've had since I purchased it. In our practice space, where I know that the power is good, I've pounded on this amp repeatedly and continuously without a sign of trouble. I've never been able to get the DDT lights to come on, and that's with the attenuators 1/3rd up, or the amp opened up altogether. I've given it loads of signal from my preamp and I've backed it way off...no problems.
Now, as I said, the past two shows I've had something somewhat odd happen. Several weeks ago we played a room that I've played regularly for a couple years. In fact, in June we played there weekly, and I used the same amp, preamp, bass, outlet, stage setup, etc. all without trouble. This one night, I had my usual setup and about half way through our set, I noticed I was getting the DDT lights flashing and I could HEAR the compression kicking in. A couple tweaks to minimize it, but definitely something weird. I believe that the circuits probably share outlets that are also tied to the 'kitchen' at the club.
...after the show, I head back out to our practice room, set up and get ready to trouble shoot. Except that...I can't get the DDT to reproduce at all. Full out, run hot and long, opened up, boosted lows...nothing. Clean and tight.
Then last week, we hit a club that, while fun, has what looks like a dodgy stage setup to me. Also with our stuff, they had about 10 lasers, some other lighting effects and smoke machines on board. I set up both my amp and a Fender Twin. The twin sounds dirty from the get go, grindy and distorted even at fairly low volume. The IPR does the same dance as the previous show, but possibly even moreso. DDT kicks in with the attenuators set at 1/3 up (2 channels at 8ohms), I back off and attenuate my lows and it's still limiting. I talk to the soundman, and ask about the power and he says 'could be...I dunno'...
Into the practice room again a day later. Again, reset the rig and pound on it. No DDT, no clipping, no limiting, no problems. Clean and perfect up to insensible volumes.