Hey Chadeffect,
Nice system! Do you have the basshorns with your Trios? How big is your room? I've got the Avantgarde Duo Primos, which is one model down from the Trios. At the time I purchased them, I was contemplating getting the Trios with basshorns. I was told that the Duo Primos were easier to set-up and did not require as big of a room to sound their best. Have you thought about acoustic room treatment for your listening room? Professional acoustic room treatment (ASC, RPG, & etc.) was/is, by far, the biggest upgrade I made to my system. I know it sounds like hyperbole, but the room treatment transformed my listening experience.
The Audiopax Model 88 tube amplifiers (look like toasters:) were probably the most natural and best sounding amps that I heard on the Avantgarde line of loudspeakers. However, those amps didn't/don't do the creamy three-dimensional harmonic tube thing (like a good 45 amp) that many tube guys tend to seek out. The SIT amp is the best solid state amp that I heard on my Avantgarde loudspeakers. If the SIT had one weakness I thought it was in the dynamics department, which I thought was a slight weakness with Audiopax Model 88's.
I'll try not to make this into a tubes versus solid-state debate since I like both. I don't want the music I listen to on my system highly influenced, changed, colored, or editorialized by tubes, cables, electronics, power, and by the room. I believe that the best sounding tube and solid-state amps sound a lot closer than most people would be willing to admit. Tube amps by Coincident, Audiopax, Art Audio PX-25, Wyetech, and Yamamoto along with solid-state amps by First Watt, Pass, and Sugden are all great sounding amps that share many of the same attributes.