Reference 3A Grand Veenas vs Avalon Eidolon

Some people would say yes, and others would say no.

Big upgrade more musical better stage depth,imaging etc.

I agree with Ebm, going to the Avalon Eidolon speakers is a huge up-grade, sound stage is one of the best in the industry.

Think long and hard. You have some mighty fine speakers already.

Shakey

In terms of all the audiophile checklist items, I would say yes, especially in terms of soundstaging. In terms of being able to enjoy your music collection, IMHO it's more of a sideways move, as the Ref 3As are extraordinarily musical (as are the Avalons). I think that the Avalons will handle large scale ensembles better than the 3As, though, based on my brief listening to both. The Avalons might require different amplification, though, and their transparency might unmask weaknesses in your source components (we don't know the rest of your system, so this is just a caution), so keep that in mind if you want to upgrade.

Grand Veenas are one of the great buys in audio. Much easier to set up than Avalons.

Apples/oranges really, but my impression is that both would play more or less in the same league and each have their fans.

The Reference 3A works very well with a wide range of amps. The Avalon not. When you go for them, the amps will give you some thinking. High powered amps AND good sound are not cheap. And the set up is much more demanding compared to the Ref 3A.

"Think long and hard" +1
There's hifi considerations and then there's musicality considerations (as Rcprince noted). Syntax makes a very valid point. It's an advantage to have a speaker that can be driven by high quality low-moderate power amplifiers. These types of amps can often provide superb sond quality.

I have heard Avalons demoed using Boulder amps only. The resulting sound was quite unique in terms of tonal balance and detail. Lots of detail and energy through the midrange I would say. It was also a fairly brief demo. I cam eout thinking there was something unique there that some would consider worth pursuing but also that I would be most careful about overall synergy and performance in order to avoid potential fatigue factors. Lots of potential...but the jury is still out for me.