The VAC or CAT will handle the Avalons with ease. The Atmasphere MA1/MA2 would be another product line I would give much effort to audition. I think it ultimately comes down to balancing with your source and preamp sonic strengths/weaknesses.
I have the VAC Phi 70 monos driving the original Eidolons. Initially I was concerned about the modest 65W but turns out there's absolutely no problems. If the Phi 300 is tuned to sound even 80% like the Phi 70s you'd have a clear winner.