During the recording of AJFA, the AJFA tour, the recording of the BA and the BA tour, James used a IIC+ and an MP-1. Do you think he blended these two amps to get his heavy sounds ?
One more thing : does anybody know what kind of tubes (for preamps and power amps) James used during this era ?
Well, AJFA was all Mesa for the rhythm. You can see that in Flemming's notes, though a good chunk was actually one of Kirk's IIC+'s (not "Crunchberries") and anther track was the IIC channel on the Mesa Quad. I don't know that James used the MP-1 for much other than cleans at that time. We know some tracks - like "One" - used the MP-1 for cleans. Kirk also used the MP-1 in a majority of the solos.
For TBA, it's possible that James used the MP-1 blended in for rhythms into a Stategy 400. He's alluded to it in interviews, and the MP-1 is clearly seen in his recording rack for the album.
For tubes, I would guess that James was using stock Mesa tubes of the era. I doubt James was personally doing any tube rolling, so they were likely using what they had from Mesa, which would have been STR 415's early on and STR 420 by the 90's.