I do want to thank you guys for giving me some suggestions. The Amperex 7308s (Telefunken, etc) I am sure sound wonderful but at least for this amp IMO, seem to be at a price range better served for a higher end unit. I was intrigued by some of the comments for the Western Electric 396a (along with other 5670/2c51 tubes) and using an adapter. I did order the adapters along with some Russian 6N3P DRs as well as some GE 5670s (both really cheap) to try. I'm sure I will roll through some others as well until I find what works best for my phones and ears. More than likely, I will get some Western Electric 396a's too. i will post my impressions when all has been received and a little break-in.