Tried all sorts of preamps during my Ascent days.
The only preamp I liked was an MFA Lumi which I eventually cloned myself.
Had a Ref 1 for the longest time when I had the Ascents as my main speakers. Open, quiet, overwhelming, and not musical.
You can't trust sand devices with small signals.
Might as well use a transformer based preamp if you dont want tube pre.
Biamping gets you the space and depth that the Avalons are known for, and using a tube amp for the highs tames the Titanium dome a bit so its less dry (Triode only, UL amps make it worse), but bi-amping is finicky and too much hassle.
You end up spending all your time adjusting the gain of the bass amps rather than listening to music.
Thats why i gave up on the Ascents. Are your TRLs S100 monos or stereo? If its stereo then you absolutely MUST biamp to deal with Radians.