440 Pro vs 400 Monoblocks

[Cadguy]

Thanks for all the helpful info and insight! Damon that's an interesting observation about the difference between musical cohesiveness and separation and definition and I suppose either presentation could be advantageous on different types of music. But certainly tone,  texture and soundstage are paramount for me. Now I'm not sure if the 440 Pro that's for sale has CI, I'll contact the seller tomorrow. I wonder where the largest sonic improvement occurs: 400 monos to 440 PRO or from 440 PRO to 440 PRO CI?