Well, I think this is supposed to be a secret (but I wasn't sworn to secrecy) and I can't really comment from actual listening experience because my unit hasn't yet arrived, but a musical instrument company called Applied Research and Technology makes a low-priced tube processor, the ART DI/O, that decodes at data rates up to 24/96, uses a 12AX7 tube, and features dialable "tube warmth". The list price is $249.95.
The unit does not upsample, but is reported to sound great, besting many DACs at much higher prices. My D/IO is in transit and I hope to receive it sometime late this week. For the price, it seems like a real no-brainer and the adjustable "tube-warmth" feature is just too cool for words. One metro-area audio society is having a meeting to demonstrate the little upstart and has challenged its members to bring their favorite heavy-hitters for comparison. The whole scenario is most intriguing, and I can't wait to see how it unfolds. I would think it would partner quite well with the DV333. http://www.artroch.com/ :)