Thanks tomic601! I would love to listen to a set of Ayre mono locks in my system too. On the tube side, I think a pair of Atma-sphere MA-1s would be interesting to listen too as well. The quatro has low efficiency but a steady 8 ohms across the frequencies might make up for that with an OTL. Unfortunately, I think my dog might be too interested in an exposed tube amp to be safe. So for now, I'll continue to enjoy the Pass.
-Karl