Because of how flimsy the output transistors are, just snugging them down onto the heat sinks will ensure max heat transfer (they slide in and out of the back planes through the "Gold Cups". A quick inspection of the back plane will tell you if the pems are in square. If you NEED the springs, or clamps, by all means use them. If you are paying attention and using the direction provided by Whit Oak Audio Design, you don't HAVE to use them. You'll get everything flat and square without them.
