I see how on a Phase Linear centric forum that the clip on heat sinks used by a major competitor would be considered cheating. But if the amp was delivered with those attached from the factory, and they were, I don't see that as cheating. If someone decides to remove the clips and the sinks then that is on them.
Look at the Sansui 9090DB receiver. It has a heatsink screwed onto the heatsink that holds the transistors and needs to be removed to pull the output transistors. Is the use of the clips vs. the screws the difference between we don't care and cheating?
The heatsinks will suck heat out of the heatsinks on the amp. There will probably be a difference between the outer pair per side which have longer original heatsinks to suck from and the inner pair which are short sections, what 7.5 inches tall by maybe a bit over an inch wide that is in contact with the add-on heatsink.
Whatever it is added metal mass in contact with the original heatsinks and if the finish is good enough on both pieces, a bit of heatsink compound (best heat transfer rate can be used since not an insulated electrical location) then these should work just fine.
As with many big amps the entire unit is the heatsink. Crown faceplates get warm and I had one, a DC-300a, that got to shutoff temp levels when a friend had the system and there was a stray strand of wire connecting the left channel red and black output binding posts. Amp lived like that for a couple weeks, run a while get really hot on the left edge (rack ear and about 1.5 inches in from the rack ear, vertically along the face of the amp) shut off, cool some and turn back on. Simple fix, amp was fine. Scott had no idea.
But these heatsinks. I think they were well bought as I stated and if they can't be used to augment the sinks on his amp they might be good for mounting smaller power resistors to a test load. Lots of things can be done with these.
