The transistors are bolted directly to the heat sink base, I didn't want to use the L-bracket, because this should have better heat transfer. Yes, I am using pure silver jumper wires. I couldn't figure out any other way to do it without positioning things really awkwardly inside the case. It works quite well, the heat conducts very evenly across all the fins in no time at all.
Waiting to replace the volume knob with this one:
