Try my Dbl Clean patch again but switch to Class A, I forgot and left it at Class A/B. That means we are running at 10 watts, switch it up to 25 watts and it gets louder!
I think you mean that the other way around? Class A is 10 watts, Class A/B is 25.
Class A will run out of headroom and begin to clip/saturate much sooner as you increase volume. For some reason (I haven't played with it enough yet to figure out why) Class A is louder than Class A/B up to a point.
Almost all power amps run in Class A up to a certain output. For example, my Parasound Halo runs Class A up to about 25 watts, then switches automatically to Class A/B when the required load exceeds the Class A bias. So, it may have something to do with the fact that you can SELECT Class A or Class A/B and "lock in" that class in the DT's, or it could be the way the power amp section in the DT's is biased. Would love for someone to chime in here that knows more about this stuff than I do.