BiAmp Focal Kanta 2 speakers with 1 set of posts.

Since you mentioned running in mono, I think what you’re talking about is running the 2 Evo 400s as mono blocks with one amp driving each speaker throughout the full frequency range…That’s definitely possible and should make some improvements, the value of which would be relative. 
 

Bi-amping a speaker means using a different amp for the tweeter than for the woofer on the same speaker. That setup would require one evo 400 driving the lows and the other driving the high frequencies each still set in stereo and connected to separate binding posts on the speakers… you can’t do that without separate binding posts unless you’re going to do some surgery on those beautiful speakers. I would not suggest this plan. 

Get the other Prima Luna, drive each channel by one and enjoy another or 2 of performance.

Maximize the potential of those speakers by getting them in the optimum position, along with attention to the room.

One of many ways to find the "perfect" spots for your speakers.

http://www.cardas.com/room_setup_calculators.php

Speaker location and room will do more than what you're thinking of doing.

 As mentioned, your speakers are not  setup for separate amps to drive lows/mids and arguably wired in a "better" configuration-single post.

Thanks for this helpful advice and link.

For me, I would do the surgery to bi-amp.

The Kanta No 2s are not a perfect match with those Primaluna amps.    The impedance dips a hair below 3 ohms and is a hard to drive speaker below about 120 hz.  Bass will be a bit flabby.  This really is a speaker that is best with warm, SS amplification.  If you really want tubes, something like an LTA ZOTL 40 Reference+ bridged mono or something from Octave will handle low impedances better.  

Full disclosure, I am a Focal dealer.  I have no affiliation with Octave or PrimaLuna and do have a friendly relationship with LTA.