Tried the AFO2 with my Vali 2/Modi 3 today.
In my experience, the Ether 2 and the first Aeon Open both love tubes, I would go as far as to say that a powerful tube amp/hybrid is a must with those.
It should, at least on paper be a good combination.
The Aeon 2 Open's impedance is 12 Ohms and it is driven to satisfaction with about 250mW according to Dan, and Vali 2's power output is:
Maximum Power, 16 ohms: 1300mW RMS per channel
Maximum Power, 32 ohms: 1000mW RMS per channel
Maximum Power, 50 ohms: 650mW RMS per channel
Maximum Power, 300 ohms: 270mW RMS per channel
Maximum Power, 600 ohms: 140mW RMS per channel
And you can hear it immediately - running an Electro Harmonix 6922 Gold Pin or a Electro Harmonix 6CG7 with it the Aeon sounds powerfull, dynamic and spacious.
I personally love the sound of the 6922 (adore my LCD 2.2pf with it), I know it's not the best - but better than stock in any way. It is lush, full bodied and holographically spacious.
It accentuates the Aeons allready present tonal characteristics (the midbass hump resonates even more) almost to the extreme - if it's to much swap in the EH 6CG7 for a more neutral and a tad more resolving presentation.
Fat tubey, holographic goodness or a bit more "airy" spacious, neutral clarity - pick your poison.
Both these tubes are noticeable better than stock and cost around 15-20 bucks a piece.
To summarise, this combo is a price/performance winner in my book - as it was with the Aoen Flow Open.
It provides the Aeon 2 with more than enough power and plays to its strenghts, plus you get the option to
upgrade tubes and modifiy the sound slightly to your liking.
Next step up, to my limited knowledge and experience, would cost at least 500 bucks.