Myles is right on the button as far as the improvements that can be had from upgrading to one Doc's Repro Amps. Really a big step up from the Seduction which will probably never be beaten as far as an incredible bargain goes (in the audiophile world at least).
I consider the Seduction to be an entry level piece of gear and enjoyed one for a while. The gain thing was a real problem in my systems.
I also agree with Myles regarding tube selection. The TFK 806s and an Amperex 7308 of your favorite flavor make the classical selections sound the best I've heard.
I've posted elsewhere that an excellent alternative tube set is a pair of GEC 4085's and a nice quiet Amperex Bugle Boy 6dj8 (I bought a lot of 16 and weeded out the quietest ones). The 6dj8 will raise the noise floor a bit but with this tube set, jazz, rock and pop is fantastic.
To get back to the original posting, with this tube set, Blackjack David's Abeline will just melt you in your tracks. The guitars being strum in each channel are so real sounding and their texture blends so seamlessly you can just about taste it! It is quite simply,.. magical!
It would seem that "magic" is a pretty fragile commodity though. One wrong move in set up and it's gone. But, as long as nobody steals my copy of the Dave Alvin tape, I can get it back and all is right again.
The same can be said for the intimacy of the Jacqui Naylor tape. As soon as I move to the control room side of the glass, I know something ain't right.
I guess that's one of the side benefits of these tapes. Since I've have them as a reference, my pals seem to think that I'm some kinda "set-up" genius (which I certainly don't profess to be)! I can still hear the textures and definition of the first time I heard the Naylor tape on the studio's monitors (Paul's Magico/Bottlehead/Bag End set up). It pretty much set the bar for me. And considering that it was when they were preparing the first running master, I don't think it's very likely that I'll forget it any time soon.