Avantgarde Trios too loud with my amps

I rarely recommend what I personally use, but the Lamm SET amps are very synergistic with the Avantgardes and will allow you to hear why both products are highly regarded.
You should probably get some help from some one who knows the speaker in setting them up properly. I've had the Duo for six years, and there are significant differences with small changes in set-up, wiring, and adjustment of crossover to woofers. They can deliver life-like sound, sound lackluster or make you run away screaming, depending on small changes in set-up.

Agreed re gain, not power of amp, but the Lamm SET/AvG combo is
special in my experience. (And yes, I have used other amps with the AvG
as well). A pair of used ML 2.1 are probably in the neighborhood of 13k
dollars US from an authorized dealer, and well worth comparing if the OP is
going to the trouble of getting the most out of the speaker/amp combo.
Like I said, I rarely recommend components I use. Interesting to note that
several other AvG owners who have posted here (Triode, Maril) have the
Lamm
and the other poster-Chadeffect- who also owns the Trio, recommended
similar types
of low powered tube amps.