Lex
I have used a few tubed preamps that I think you may want to consider.I really like the Synthesis Harmony preamp.It uses 12AU7 tubes and is a true dual mono unit with lots of gain.It is super quiet and sounds awesome.It seems to match well with many different amps.It sells for $1000.00 but can sometimes be found used on Audiogon.
I also love the Rogue 66.I have used one for a while and think it is way underated.It does not have as much gain as the Sythesis but sounds very good and matches well with most amps.It sells for about $1,000(street price) too and is available with a very good phono stage.
I have used the AES AE-3 and found it to be very good and sound great.It did not match well with some of my Low powered SET amps and does not provide a lot of gain but it sounds very mellow.This can be good or bad,depending on your tastes.It sells for $600.
If you can find a Van Alstine Pas 3i used for a good price,try it out.I built mine from a kit and love it.It has a very modern tubed sound.It is not slow or sloppy like some tubed preamps and has lots of inputs and outputs and a great headamp and one of the best built-in phono stages I have ever heard.
I am a big fan of the Rogue 99 preamp(magnum version) and use one currently.It too has a very modern tube sound free,from any obvious mush or slop.It has a seperate power supply a good headamp,great phono amp and lots of gain.It has matched well with all my amps.It sells for $2800 in the magnun version with phono stage.
As much as I have downed the ASL Twinhead for QC issuses,I did think it was one of the very best preamps I have yet heard.The fact that it stands as one of the best headamps ever is added bonus.It sounded magical in a way that only a 2A3 based tube preamp can.The dynamics were huge and it had a soundstage that seemed to expand across the entire room.This is one of the preamps that I think could make just about any amp sound world- class.I think you should really try to give one of these a listen.I hope Joe Lau has remedied the QC issues.If he has indeed,then this is the preamp to beat.I think the price is still $1250.