Ok … my experience .. the only Pass which can push SL – especially Non-Px panels is X350.5 and even better X600.5. XA – 60.8 is a joke. SL is electrostats and they are driven by voltage – it means they give their maximum with tube amps. I had good experience with JC-1s and Pass 350.5 but if you want to have the best from them – use tubes! Now panels are very efficient and 100w will be enough !