'Cane, there's no way to guarantee ahead of time that any unit won't shut down in an extreme condition; there're too many variables that affect the situation. Generally speaking, the 74TXVi has plenty of power into 4 ohms and it's likely to work well, especially since you have your excellent sub in effect doing active biamping and taking a lot of the low bass load. In the unlikely case that it wouldn't be enough, you could later do as Ryan(BassTek)mentions and add a separate amp just for the M80s. At this point however, you shouldn't assume a problem which probably wouldn't develop. By the way, although the Denon manuals are exceptionally miserable, don't let that stop you if a unit like new 2807 attracts you.
