Building a system from scratch (other than speakers)

Is your $5k budget for preamp and a amp or also for the Pro-Ject and Oppo you mentioned?  If $5k needs to include everything look at the Parasound Halo integrated. Great unit for the money which I believe has phono and a DAC under the hood, but suspect the Oppo will sound better on its own.

ModWright KWI 200 w/ optional phono board. The Pro-Ject is a nice deck and I bought one, "Purple" for my teenage daughter. I'd buy used on the table and step up in the Pro-Ject line. Clear Day balanced cable to the Oppo 105d. Call Dan at ModWright; he might have a demo unit and he'll tell you how his amp will work with your ML's. 

I have Aerial Acoustics 7Bs and I bet your ML's need power as well. Like my Aerial's they work with a 100 watt amp but you won't know what your speakers can sound like until you feed them the power they need.  I might be wrong but look for an amp with 200 watts that will double down. 

Good luck

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