oh, man, i've never liked the voltage output on my sunfire anywhere near as well as i've liked the current output and i've had quite a few speakers to try them on.
they sound good on bass drivers, but not as good on the mids and tweeters, IMHO. the configuration is fun to play with, though.
if i recall, the surrounds are all voltage, but it doesn't matter as much there. the cinema grand mark ii has the optional current output for the center channel as well, where some iterations of the amp don't (i later discovered i don't like center channels on principle, but that's a different story...).
good stuff, glad you're having fun.