Am trying to find info on the differences between the ref7250, 7270. With the new ref200.5's and .7's coming out, good deals are to be had on these older amps. Is anyone aware of the differences? Can't seem to find info anywhere And how hot *does* the B&K line get? Prefer not to have an oven in my rack! Am also considering the Sherbourne 5/1500A. Any thoughts on how these 2 would stack up aganst each other, performance wise. Sherbourne is chaper, so that might well be the ticket. Thsnks!