Bvdiman, I do agree that Accuphase amps are conservatively rated, however I don't think the Spendor's minimum impedance is relevant. It is specified at 5.5 ohms, but Stereophile measured it at ~6 ohms, and showed it to remain above 8 ohms most of the time. Also, the calculator I used to determine the numbers in my post, factors in 3db headroom for the amp, which is a double of power.
Again, I agree an Accuphase amps' power will increase dramatically into lower impedance loads, like a 4 ohm speaker dropping to 2 ohms. The Spendor is just not that type of speaker load.