There are rackmount ears available (see this page for the ears used with most rack-mounted M200's and this thread for a detailed discussion of rack mounting M200's).

Outlaw has said in the past that it is acceptable to stack up to three M200's safely. One of their main concerns for larger stacks is weight - M200's are heavier than they look, and the weight being carried by the bottom amp in a stack adds up fast as you add amps. Some people have stacked as many as four successfully, but I'd try to keep the stacks down to three. If you had five, I'd set them up on two separate shelves.

As for the triggers, Scott had this to say in an older thread :

Quote:
The trigger will accept as little as a 6 V DC 4 mA signal. However, since many of you will likely be using higher voltage and mA triggers you should easily be able to trigger seven or more of these amplifiers.
_________________________
gonk
HT Basics | HDMI FAQ | Pics | Remote Files | Art Show
Reviews: Index | 990 | speakers | BDP-93