Building a system from scratch (other than speakers)

Celtic66,
I'm a devoted owner who immensely enjoys a SET 300b amplifier. The Allnic you cite has been praised universally.  However I believe that his speakers would be better matched with a good quality push pull tube integrated /power amplifier  (good output transformers and stout power supply ). I'd really recommend looking at used  amplifiers to maximize purchasing power.Line Magnetic and Quicksilver are a couple of good tube brands to consider. 
Charles, 

There's many SS amps and integrated amps that will sound great on your ML's. I've heard the Parasound Halo Integrated on Magnepan 1.7i - 3.7i and it's a really nice amp; not harsh or thin and drives the Pans with plenty of power for most. If you can spend more the ModWright and Pass gear is hands down better and your speakers are in my opinion more in that league. 

Not sure how extensive your vinyl collection is but maybe start with the digital side first and add the analog gear later when budget allows. I wouldn't skimp on the amp too much with your speakers. 

I'd forget a tube amp on your speakers unless you can drop some serious coin and want to deal with the cost retubing such a beast you'll need for your MLs.

Call ModWright and see if Dan has a show demo on the KWI 200. He knows as much as anyone does on the Oppo you're interested in too. If he has a demo and is willing to part with he'll give you a good price.

In my opinion, if you don't step up to a high end Integrated amp such as the ModWright you wasted money on the MLs. The ModWright KWI 200 will get close to tube sound without the cost and headaches down the road. Only mention Integrated as you'll spend a lot more for separates and cables to do better.

If you're using your Theos in a home theatre set up with a receiver you have not heard your speakers yet. Hopefully you have a dealership near that has something you can drag home just to see what your speakers can do. A lot of people bash MLs because they've only heard ok gear on them; they're very revealing so crap in - crap out it goes. 

Good luck

Arising, I too have an ESL system. I had Quad ESL57's, then ML, now modern Quads.

I have used tubes (good sound), and solid state (good sound). But here's the thing: ESL's tend to have circuits to protect them from high voltages caused by equipment failure (or owner failure, I suppose). They rob performance from your speakers. It would be great to remove them.

If you were to choose low power, high precision solid state amplifiers, it would be impossible to drive the speakers loud enough to engage the protection circuits. Therefore the protection circuits would be redundant, and so they could be removed. This I have done, running without protection circuits for nearly 10 years now. Practice is the same as theory - no problem. No problem whatsoever.

Caveat - my electronics are all ultra-stable full complementary push-pull home-brew, designed for low voltage and high precision. YMMD

I should have added: perhaps the electronics are not optimal, but the SYSTEM is.