Thought I havent used the new Triode amps, Ive used both the Silver 60s and Silver 90s amps from Quicksilver with my Audible Illusions Mod3a preamp for some time (before selling the amps and going SS on the bottom). The midrange is as Mike points out super smooth and silky... Depending on the room size and speaker selection its a winning combo.
As for the AI, theres a lot in print here and elsewhere about the product and company. Ive have zero problems with mine and its a great bang for the buck. Put some Russian military NOS tubes in it and sit back. The preamp adds little to no color what so ever and is dead quite. Personally I cant say enough good things about the preamp, plus it has a very good phono stage. (I had the mod3 which I had upgrades a few years back to the mod3a with a custom 17 faceplate.) There are very reasonably priced on the used market, however please read the threads on customer service.
One last note, there is absolutely NO comparison between the QS line stage and the AI Mod3a. The AI is just a killer preamp (for the money).
Good luck
Tony