Clean tone is largely a function of headroom, and it mostly controlled by the power limits of the preamp/power tubes and the construction/number of the speakers used. While you can get a squeaky clean tone from a 15 or 20 watt amp, it will only do so to moderate volume. On the other side, pushing a larger wattage amp to distortion often makes them oppressively loud. A lot of words for a simple reality: your amp has to fit your environment in order to get the clean/distorted tones you want at a volume you can use.
As an option for higher powered amp than your space/ears/neighbors can tolerate, you can get a device like the UA OX Amp Top Box and make it work. You can’t really ramp up a quiet amp as easily without a PA.
Option 3, and something that’s really come along since you last amp purchase, is modeling. I use the Fractal Audio Systems Axe Fx III, and there are other good ones as well. That’s a whole other discussion!
So if you’ll share a little bit about your intended uses (gigging/home/neighbors) and music styles or maybe some artists or songs that are examples of what you’re going for, and the guys here can make suggestions from that. You have an awesome and flexible amp already, so you can take your time wading in. The IIC+ is one of the amps I’d like to add when I can, so you’re in a good place.
BTW, I’ve never owned or played a Dumble or Trainwreck, but they sound very different to me on recordings. The Two Rock I played was more mid-focused, maybe between the brighter, grindier Trainwreck and the more muscular sounding Dumble. The only amp I have that’ll bridge that much ground (besides the Axe Fx) is the Mesa Road King II, due to its ability to mix and match power tubes. I’ll be interested to see what suggestions come up here!
