A lot of ears I trust over on Audiogon really like Aric audio, and he seems like a great guy to work with. There are a lot of competitors in that 6sn7 space (Aric audio, Don Sachs, deHavilland, Supratek, etc.) and given the listening reports, I personally suspect that many of them are more alike than different. If I were going down that path again, I'd probably go with Aric or Supratek. As I'm sure you've seen, the reviews are almost universally positive. I did really like my DS preamp, but the purity and clarity of the DHT sound shocked me. For commercial options in the DHT realm, you've got the above-suggested KR Audio, plus Coincident, Allnic, Vinnie Rossie, & Thomas Mayer (the favorite of many WBTers in the high efficiency crowd). I'm sure there are more that I'm missing, but not a ton...