I used the Z5500 for a couple years on the senior circuit, more than adequate. A word of caution, though. DO NOT place the remote control receiver on top of the sub woofer, especially at high volumes - the deep vibrations of the sub will destroy the receiver. How do I know this, I blew out 2 of them. Logitech replaced the first one at no charge under warranty, however, the second one was a couple years old so no freebee. The service tech guy filled me in on why both of them were blown out. Keep in mind this thing is 1,100-watts peak power and 505-Watts RMS power.
Good luck,
Gary