I think the normal trick is to "hang" the foam panels on the wall like pictures rather than glueing them like panelling. Having a bit of air space behind the foam doesn't hurt, in fact IIRC it extends the damping effect to include lower frequencies.

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8