Tube substitute

You're likely already doing really well with the 5692s. I ended up going with them on my Blue Circle BC2s after trying many others. A couple of tubes that are supposed to be even better are ECC32/CV181 type tubes, in particular those made by Mullard. Also, I am given to believe ECC34 may be even better than those. I haven't tried them though. I don't know about the other tube type you mention. Good luck.

Saxman, just to follow up - yes I agree with Ed - definitely check whehter the EC32 or 34 would indeed work with your system as they are not 6SN7 tubes but in many cases would work fine in that position (I checked with Supratec to see would they work for my upcoming new preamp and they confirmed that they would work fine, but maybe they wouldn't work for certain other amps). Also, I concur with Ed, the US tubes are typically the best. My understanding is that the best 5692 tube is the RCA Red Base, which is what I bought. Good luck.