I ordered a QA-001 from Albert of Space Tech Labs about this time last year, with an additional set of inputs to accomodate two sources. The preamp replaced an NHT Passive Volume Control to my Carver ZR1000 digital amp. Honestly, I have very little experience with preamps, but compared to the NHT the tubed QA-001 was better in every way - great dynamics, wider soundstage, excellent detail. I found that it pairs extremely well with the ZR1000.
When you order one of his products, Albert queries you about the sound you are looking for, as he will hand wire the component to your preference. This isn't something one expects when buying audio gear under $500.00. The only down side I can think of is that the case is made out of some kind of funky light weight material. I plastered the inside with Dynamat, effectively doubling the unit's weight, and used ERS cloth with good effect.
Again, I don't have a lot of experience with preamps, but I believe that Space Tech Lab's products are at the very top of the cost/benefit ratio.
PS. Dmason offered that I love the QA-001 as much as my parents. In truth, while I adore my parents, at their advanced age they simply cannot compete with the dynamics and live energy of this amazing little preamp. Sorry m & d.
Matt