Yup. He talks about it in an interview. He had a built in preamp in his guitar for all that extra gain...although Mk2s have a lot of gain. My 2C non plus has plenty...like a boosted 800 or even double boosted.
I wasn't endorsing how he set the things, just posting what he did w/ them. Those amps have a lot of variety of sounds in them to be discovered.
I have a MKIII Coliseum Simul-Class head (no stripe) that I've owned since new in 1986 (S/N# K513-- 13th produced out of approximately 200), which I prefer to the MKII Coliseum- of which, I've also played quite a few.
The intro is the Boogie on the R2 channel, solos Boogie lead channel, heavy rhythm sections are a Cameron modded Marshall SLP
On this one the heavy rhythm is also the Cameron modded Marshall, and solos are Boogie MKIII Coli