The Fulltone OCD worked great for me. I had a 2x12 Mav and I found several OD 's to be too dark and compressed. I'd stay away from Tube Screamer types as everyone I tried from TS9 to Maxon sounded like a blanket was on the amp. The OCD was very open and did not mess with the Class A amp. The Wampler Euphoria is another one that seems to work well in front of Class A although I only have played that one in front of my BADCAT Cub and never tried it on the Mav before ditching the amp. That sucker was heavy man.
I'm a huge fan of the Xotic BB Preamp. It gives you that warm Marshall overdrive by itself, but it makes every tone better when used as a mild boost. Seriously, it just magically improves everything on my Mav 212
I used to have the 2x12 and I agree with what has been said. Great amp. Likes to be played loud.
Crank the masters and use volume 1 to set your level.
I remember getting a great tone that way. Fat sound for single coils. Worked great for me. My strats loved it.
I used to love my Exotic RC and AC Boosters in front of that amp. KOT also.
The cleans and light breakup sounds are fantastic when pushed a bit with those pedals and the volume up.
Real vintage sounding cleans.
I bought a Maverick Proto shortly before the production Mav came out. I used it for about 10 years with no pedal, the lead channel had plenty of gain and very thick, great for bridge pickup soloing but too thick for a neck humbucker, IMO.
My son uses that same amp now and he always uses a Boss Blues Driver on the clean channel and only recently started experimenting with the lead channel.
Barber 1/2 gainer with mids opposite the amp setting, ie., high on pedal if under 9:00 on lead channel of amp; or, under 9:00 on pedal if above 10:30ish on amp.
THD Hotplate with master at 10:00-noon and channel masters at 10:00 to noon. Attenuate 4-12db depending on situation. When the power tubes are driven harder, this amp really takes off!! Lots of edge and attack come out that you miss at lower power amp settings.
I have a 2x12 combo with V30s; used to have a 1x12 combo with an alnico Eminence Redcoat. That combo loved the treble boost.
I would like to clarify that I'm looking to goose the lead channel for girthy rock riffs and sustaining solo type leads. Some tasteful chugging may ensue. So far really digging the amp and like both channels. Just looking to take it to the next level.