What is the best tube pre for $350 used? HF detail

Google Pacific Valve Company. They have lots of reasonably priced equip- NEW, too!

The Cary brand known as AES I forget what the letters mean. The original AE-3 pre-amp sold as a kit or manufactured for you beats the living daylights out of any other preamp I ever owned and is just about the best I have heard. They cost an astonishing $300-$350 used. They only make the modded up DJH signature now which is about 3-4 times as much. The plain one sounds as good as the modded one so try to get a plain.
The unit uses two tubes both 6SN7s and has one big trafo. Looks like a toy plays like a big city orchestra.
I was stunned, my buddy a preamp designer himself said WTF that is Scary good. No joke it's pieces like this that makes sense that will make it through the coming financial storm
The only caveat I have is that I collect 6SN7s and have been using some of the more desirable ones around. You don't need the most difficult to get or the most expensive. However I would invest in a good (decent) pair if I were you. Afterall you just saved thousands on the pre!

Thanks a bunch guys. Will look into these. The Cary in particular sounds like a winner.

I've had my head in the budget preamp space for quite a while.

The Bottlehead Foreplay III stands out as one of the best bangs for the buck, but it's slightly more than $350. A new unit is $449. They're hard to find for less b/c owners usually modify them with better caps, volume attenuators, etc. Building a kit is a great learning experience if you're into that kind of thing. Bottlehead gives great support and there's an active forum to ask questions.

AES (Audio Electronic Supply) is owned by Cary. They used to offer kits, but don't anymore. I had the standard AE-3 for a while and found it to be bloated. At times, the bass was out of control which muddied the midrange and skewed the whole presentation. I was using RCA Red Base 5692 and Sylvania 6NS7GTB at the time -- neither are known for being muddy, so I can only attribute the bloat to the preamp. You can easily find the AE-3 for $350. It's certainly not a bad preamp. It has a silky midrange, smooth top end and it's very quiet which is hard to beat for $350. If your speakers are bass shy you might find a nice synergy. It might work well with monitors.

There's a big difference between the standard AE-3, the DJH and the AE-3 MkII. Kevin Deal from Upscale Audio had this to say about the three:

With the regular AE-3 and now AE-3 Mk 2 the bass can be a little bloated depending on the application, but the AE-3 DJH’s front end topology is slightly different. It is direct-coupled, meaning there are no coupling caps between the input and output stages, which makes the preamp much more dynamic. I think it has incredible bass, great imaging, airy highs.

I now own the DJH and positively confirm what Kevin says. It isn't bloated in the least. It's a completely different beast compared to the standard AE-3. The bass is fast and tight. Overall, it has a nice balance between warmth and detail. IMO, the only drawback is the gain at 20 dB. They sell for roughly $750-800 used.

I had an Audio Experience Symphonies V2R for a brief period of time. I paid a ridiculously small amount for it (something like $300). Unfortunately, my unit had a loud buzz that turned out to be a circuit problem. Despite the noise, it was a surprisingly nice warm sounding preamp when the volume was cranked up. I decided to return it rather than have it fixed. New it's $448 plus shipping from China.

I've heard a lot of praise for old Dynaco Pas preamps. They sell on eBay for $150-300 depending on the condition. There's an active community of folks who restore them. They claim it sounds phenomenal. I haven't heard one to confirm, but if budget and performance are your priorities, you might check it out. The only downside is they look dated.

while upgrading from from a cambridge audio c500 this year, i ended up trying 2 tube pre's. first a cayin sc5-s(sp.?), then a music angel. the cayin is built like a tank, has a great remote, and sounded really good(at least to my ears!), but the music angel was much better. if the music angel had a remote, i probably would have ended up keeping it. on some music, i actually prefer it to the classe dr6 i ended up with. so good for so cheap it's almost stupid.