This hasn't been my experience at all.
This is a clip of the Bogner UU in Ultra mode with the gain at 9:00. Boost OFF. Metamorph set at about noon.
Guitar bridge pickup engaged, guitar volume on 10. No noise gates active anywhere. I was sitting about a foot away from the amp when recording this just a minute ago.
The noise here is almost imperceptible. It would be negligible in a mix.
This is a clip of the Bogner UU in Ultra mode with the gain at 10:00. Boost ON. Metamorph set at about noon.
Guitar bridge pickup engaged, guitar volume on 10. No noise gates active anywhere. Same deal, I was sitting about a foot from the amp.
This clip has some noise, but again, the Boost was set to ON, there were no noise gates active, and the guitar volume was on 10. But even with the Gain only at 10:00, that's a ton of gain you're hearing there. Even as somebody with an unhealthy obsession with distortion, I would probably never go higher than that under these settings. The way the Gain knob works in this mode is a bit non-intuitive and the knob only has a very small usable range like this. It helps to remember that the channel 2 Gain knob's range and taper were designed to accommodate every mode in channel 2. The Gain's taper makes a lot more sense when you consider it has to work with the Crunch mode, boost off as well. In Uber mode with the boost set to ON though, 10:00 is about as high as I'd recommend even the the most heavily corpsepainted black metal guitarists dial the gain.
Even still, the amount of noise is in those clips is nothing any noise gate on the market couldn't immediately take care of. Also, Ultra mode uses 7 gain stages which is nuts, so yes, noise is just going to be a factor here. Any amp with that many gain stages with that much gain is going to produce noise.
Overall though, very little noise for the amount of gain. If you're experiencing "uncontrollable squeal" under these settings, I dunno, did you have the master and channel volumes dimed, and were you standing right next to the speaker, using non-potted pickups? It's easy to dial in the gain and engage the boost in Uber mode and the gain and noise will be managable with the Gain around 12:00-2:30 or so, but when you just flip the switch to Ultra mode, the noise floor is going to blast through the ceiling and be literally as loud as the guitar itself.
