Im looking for the next upgrade. I'm not real sure which way I want to go Help!

I use a pair of ML Impressions with an ARC tubed preamp and a Classe two channel amp. It has delighted me for years, and I have never felt a sense of fatigue and or any kind of thin sound. 

I would recommend a Audio Research tube preamp. This would be the next step in refinement and fidelity. I would recommend buying used and look in the $5K range.

Enthusiasm for this pursuit is key and admirable. The increases in fidelity are nearly limitless. I have been pursuing this for over fifty years and each upgrade during that time has rendered my system’s sound better and much more enjoyable. But to get the very best sound requires a great deal of planning and research.
 

You have done really well so far. I think after purchasing a great preamp I would spend a lot of time listening and learning before embarking on the next steps. As you move on you will want a well thought out game plan for future upgrades. I recommend Robert Harley’s The Complete Guide to High End Audio as a great place to get the lay of the land.

Room acoustics!!!

Slow way the heck down. It all takes time. 

Big thing is your room and getting your ML's setup right. 

@pvmike I owned ML Montis and heard 11A and 13A several times. I would describe the sound as smooth, never in your face. The presentation is pleasant but does not excite nor is it extremely engaging. It’s more about striking the balance and keeping away from potentially crossing over the boundaries. These speakers play it safe  

I think going with a good tube preamplifier like the ARC Ref series will definitely be a significant improvement compared to the preamp section of your streamer but I wouldn’t bet on the overall presentation to yank you out of your chair and cause you to start tap dancing. That’s not what the MLs are about. If you want that type of excitement you need dynamic speakers that can do that.
Just my opinion.