I have some adcom amps that would just love to help you on that .17ohm load. I here that they have been tested down to .0625ohm before and lived to tell the tale, but me, i just run them at an easy 8-4ohm.
Typicaly the adcoms come close to doubling the power as the load is halfed. A 4402 will put out 40w into 2 channels at 4ohms 80w/channel at 2ohm, and a mono load in 4ohm is around 140w. There are no published numbers after that, but going in that trend, anything less than an ohm would be some serious power.