The T773 has a better processor and just sounds better regardless of the amp you put on the T743. Get the T773 and if you want to upgrade put a 2 channel power amp on the T773. Gives you super power on the front 2 and sufficient reserve for the rest.
thanks. any good suggestion for power amp? NAD? Axiom?
I have to agree with Art, the T773 is a phenomenal unit. I have one myself. As far as amps go you may want too look at the NAD S250. Had one of those with my previous setup(56TXi/NAD S250). Depending on your budget checkout www.saturdayaudio.com They seem to have NAD deals all the time.
NAD matches its own power amp well. I'm using a Hafler 9505 (250 x 2 into 8 or 375 x 2 into 4) which I picked up used in pristine condition. It REALLY works well with my NAD gear. Almost (almost but not really that close) gives it a tube like quality. Mac is good but very pricey.