Bryston makes a line of monoblock amps (called the PowerPack) that are specifically designed for mounting on the speaker itself, on the wall behind the speaker, etc. There are several different power ratings available: 60 watts, 120 watts, and 300 watts. For more info, here is the link for the 120 watt version:
http://www.bryston.ca/pp120sst_m.html
http://www.bryston.ca/pp120sst_m.html