Please Recommend Highly Efficient Floor Standing Non-Horn Speaker Suggestions

 You have to listen Bache Audio-002 , i am in  Brooklyn, i can offer 2 weeks trial listening time with no any obligation 

I recommend Nola Contender 3 floorstanding speakers or the upgraded S3.  I have the Nola Boxers, which are the smaller 2-way bookshelf, and think they're voiced really well and sound wonderful.  The Contender is 90db sensitivity at 8ohms impedance.  Should be easy to drive with your MC275. Good luck in your search.

Prana Distribution has the highly raved Camerton Audio Binom 1.2 speakers and Binom-ER Headphones now.

I responded earlier giving a recommendation for the Tekton Lore speakers.  My prior systems consisted mostly of tube gear.   I just picked up a Rega Brio integrated amp and honestly I’m blown away at the performance of this piece for the money.   Paid $300 used and it’s the latest version.  At 50wpc way more than enough power for the Lores.   I am biased towards tube gear but I’m amazed how musical some of the modern, modest priced solid state gear sounds these days.

Very surprised I'm only the second vote for an obvious recommendation in response to the OP's question: TANNOY.  

Spatial audio.