Well the Black Treasures are in the system and running through one of my demo playlists (see details below) and I can't say that it is love at first listen.
Overall, I feel like the sound has taken a step backward when compared to my TSRP's. The music is less liquid, extended, and airy sounding. There is a bit of harshness in vocals and definitely less body and depth. While the bass draws more attention to itself than with the TSRP's, it is less tight and articulate.
Keep in mind I only have about 3 1/2 hours on the Black Treasures and reserve the right to change my views and thoughts as more hours get on the Black Treasures. I also don't have the Herbie's Rx Tube Dampers on them like I did with the TSRP's.
Demo Playlist (thanks Rydenfan for the great selection):
Corinne Bailey Rae - Like a Star
Kate Walsh - Your Song
Ray LaMontagne - You Can Bring me Flowers
The Decemberists - The Crane Wife 3
Ben Harper - Burn One Down
Ben Harper - Lay There & Hate Me
Michael Franti & Spearhead - Never Too Late
STS9 - GLOgli
Medeski, Martin & Wood - Miami Gato
Pink Floyd - Another Brick in the Wall Pt.2
Dave & Tim - Seek Up
Charlie Hayden & Pat Methany - First Song (For Ruth)
Phish (7/6/98) - Ghost
George
Well I have about 125+ hours on the Black Treasures at this point and I can safely say that they have changed since the the first few hours of use. Accordingly, my impressions have changed as well.
The most noticeable change is in the bass. Things have tightened up considerably - in fact, I am getting the best bass yet in terms of slam and drive. I still do feel that the TSRP's have the edge in conveying the shading and nuances though. But if you really want to rock out...I don't think the BT's will have a peer in this area.
Some of the harshness I was first hearing with the BT's has smoothed over and the sound is definitely less fatiguing than during those first few hours. Still not as organic and liquid sounding as the TSRP's though.
Sound stage has opened up and is more well defined with BT's now, but it isn't producing the same front to back depth that I get from the TSRP's.
If the BT's don't continue to change and improve, I am not sure whether I would pick the TSRP's or BT's as my primary 6SN7 tubes for the Modwright. Previously, the TSRP's were my clear favorites over other very nice sounding tubes (Raytheon, Ken-Rads, Sylvania, etc...), but now I feel like there isn't a clear and dominant choice. Each has some very strong attributes that I prize and choosing one will be tough.
Let's see what another 100-200 hours brings.
George