The RSC200 is actually a 4 ohm load, not 8 ohm, and from what I've read it's not the easiest load for an amp to drive. The Model 2200's up to the challenge, but it is likely to run hotter when driving a bigfoot than it will when driving an easier load. At the SPL levels you mentioned in your earlier post and in light of the fact that you've pushed the amps into thermal protection, I would say that a bit of extra breathing room would definitely be worthwhile.

Think about it this way: your system draws in the neighborhood of 9 amps under peak conditions based on your earlier post, which equates to 1080 watts at 120V. Let's assume that 75% of that (6.75A) is from the amps, and half of the amp's consumption ends up as heat (both are approximations only, but they give us an idea of scale). That puts 400W of heat coming from those five amps. Now think about what a 60W light bulb feels like (keeping in mind that some of that 60W bulb's energy is actually light rather than just heat) and multiply that by six or seven - that's the amount of thermal energy being dissipated by those five amps. The amp driving the bigfoot should probably be at the bottom of the stack (so it doesn't have heat from amps below it) along with the RS550's, with the RS1k's amps in a separate stack. Both stacks of amps would then benefit from as much breathing room as possible.

Thanks for the advice Gonk. I already have the stacks set up the way you suggested it. Surprisingly the problem occurs more often with one of the RS1k rather than with the center. Well, I pulled the trigger on the Salamander audio rack with custom adjustable shelves. It should get here by next week. As soon as I find time to rewire everything (what a pain in the you know what!) I will give the system a 'good work out' and see what happens. As this rack is open on all four sides and I plan to give the amp stacks 3'' at the top each. I shouldn't experience any more problems, right? I will keep you posted on the progress.

The comparison with a light bulb was quite fitting as the amps get SO hot that I would burn my fingers if was to touch them for more than ~3 seconds.

Open sides and 3" clear above should be a great arrangement. Let us know how the system runs in the Salamander rack.

Finally, I got the rack assembeled and loaded the components. The rack looks good ad is very sturdy. It accomodates most of my gear without problems and I think I gave the M2200 enough breathing room. I would have posted some pictures but the set-up is not complete as I am still waiting for the balanced power supply/stabilzer. I hooked everything up and gave it a try. The M2200s still get quite hot when playing at ~105dB but I can still touch them without getting burned. I still have to run an endurance test (couple of hours at high volume) to see if the amps stay out of protected mode. I still haven't figured out how to organize the cable mess in the back (other maybe then using cable binders). Any suggestions?