The above pic shows the effect of the 2nd gain control.  This is area between the 2nd and 3rd gain stage. The lower red response shows the JCM type which would be considered the starting point.  There is a bump in gain maxing at about + 17db.  Perfect IMO.  But notice the frequency response.  You can’t just willy-nilly add gain, it has to be tailored!  The frequency extremes get very little bump in gain.  You want the bump to be in the GUITAR’S range, not in the sub 200hz area which will make the tone flubby and ill-defined nor in the 5khz+ area as that just doesn’t sound great.  Guitar speakers above 5K at high levels are pretty nasty.

Here is a comment from an M-Class customer, this one a 6V6 version:

“The 822+ is by far my all time favorite amp. It has beaten out some hefty competition since I’ve received it. I even tried Ceriatones 2202. Sure it was pretty, but the 822+ had a better noise floor, better master volume, better low volume tone, and just a more authentic feel and tone. I just felt I should let you know how incredibly happy I am with the 822+”

Going forward I think I will make the depth control optional – because in all the amps I have built and had it, I NEVER have used it.  It is not something that is needed IMO, but if you want one – no problem. 

The stock M-CLASS M800+ does not have an effects loop, like a regular JCM.  However, I can add a loop if you need to insert some time-based effects after the distortion area.

The M-Class has a very useful bright control and feedback level has been optimized for best tone.  It’s funny how in M-style amps that a many decades have wildly varying amounts of feedback.

Here is a comment from a 20W M800+ purchaser:

“This amp is a beast. I’m getting the best mean thrash tones I’ve ever had. Cleans up very nicely too! Doesnt hurt I’m running it alongside a Phaez M87x for a stereo setup. Unreal tone.”

A comment from a purchaser of the 50W M800+: “It is absolutely killer, I get compliments on it all the time. Thanks Randy”