Hmm, I've never been one for having a lot of midlevel amps. Basically my philosophy is get one really great amp, and a portable amp if portable amps are your thing. I understand multiple flavors of headphones, because they can be all about tradeoffs. With amps, to me, it's more like better is better. Once you have a truly great amp, if you have the budget, maybe get an alternative.
I'd maybe go Lyr2, given your headphones, even if I had to sell the Vali to get there (especially if it's the Vali 1 and not the 2, which is a bit high on the output impedance side for some of your cans). Then you've got a world class amp that I know works excellently with every can you own (have tried out all those combos except the Momentum 2). And if you want to get some LISST you can even have solid state or hybrid in the same amp, depending on your mood. The Lyr2 is also so versatile that you'll never really have to worry about synergy in your future headphone upgrades. You'll get way more enjoyment out of a single Lyr2 vs being able to pick and choose between a Magni, Vali and 02 (or whatever solid state you picked). And if you just have the "fiddle bug" there's even tube rolling with the Lyr2.