Craig, among the few changes the most significant is probably the Audyssey Dynamic EQ feature which continually adjusts volume levels at frequency extremes to compensate for lesser audibility at lower levels and does the same for the relative volume level of the surrounds. Some of our members with older Denon 3808s, which originally didn't have that feature, paid $100 for an upgrade and have been pleased with the results.
It depends how good of a 905 price that you've seen, but the
Accessories4less price on the 906 factory refurb looks pretty good.
