I recently switched to a rack rig and have been in the market for a midi programmable preamp. I've tried out a bunch of them (I know a lot of guys who have some pretty cool toys) and have come to the following conclusions:
1) Very few high-end preamps are fully programmable. The Engl E570, for instance, has the ability to store a handful of presets... but only a handlful.
2) When a manufacturer does try to sell a tubed preamp that is fully programmable, they usually get their ass handed to them. The Engl E580, H&K Access, and Soldano x99 Caswell are all off the market, and they are all rare enough to make the used prices prohibitive. My favorite it the Soldano x99 (I know someone that owns one), but the least I've seen one sell for is $3300. Even more budget-oriented models like the Rocktron Piranha (which was acually a damn good preamp) usually fail in the marketplace.
3) For some reason the only way a manufacturer can generally sell a tubed midi preamp is to include a full suite of FX... which usually means making compromises to bring it in at a price point. The Rocktron Prophecy and most Digitech pres suffer from this problem; in many of these products the tube is not much more than a light bulb and doesn't really affect the tone much.
4) Things are regressing. Many of the best-sounding preamps on the market today aren't even midi switchable. Take the Mako MAK4, for instance. It sounds amazing, but I would never buy one. It takes up an insane amount of rack space, and a guitar preamp without midi in 2012 is just plain stupid.
5) The damn dumb retro craze that started in the early '90s and killed rack gear as a major force in the music marketplace still hasn't gone away, and shows no sign of doing so. This is also why I can't walk into a even a big music store and look at a high-end guitar with 24 frets and a floyd.
6) For reasons I do NOT understand, the only people interested in the power and flexibility of a rack setup are the people who are into modeling gear. Which I'm not the slightest bit interested in.
7) What all this means is that the guitarist who wants a full-on midi programmable tubed preamp is pretty much fucked... or at least limited to a small handful of options. The Marshall JMP-1 is now off the market (and never sounded that good to my ears, anyway), and the Mesa Triaxis is, like all Mesa gear, stupidly overpriced. There really isn't anything else out there anymore.
I wound up going with a vintage piece; an ADA MP-1. I actually got two of them; one to mod and one to keep stock.
