The jump from D200 to D400

[Damon]

The tracks I am finding bright
Swim Deep - namaste
Birdy - skinny love
Foals - mountain at my gates

That was interesting; a good suggestion by Thumb. I listened to each of these tracks several times, and I think that there is certainly 'brightness' in each. The Swim Deep track is quite aggressively mixed, almost with a scooped EQ and there are a lot of instruments mixed at top; the cymbals and snare, the organ and the vocals as well. Nothing laid back there.

The Birdy track is also quite trebly. She has a vocal balance that is more 'throat' than 'chest' in her voice. Airy, but definitely with some of the twang that I might otherwise associate with some female country singers.

The Foals track is great, but very heavy on the hi-hat. I listened to this one at a low volume as well as at a high volume. Even when turned down, and well out of the normal listening zone the hi-hat is very present. The keyboard is also right up there and forward in the mix. Turn it down and keyboard is clear and present.

Here is a funny one; I actually have the treble turned up to +2.5 on my system. My speakers use the (ScanSpeak?) ring radiator tweeter, which is not an overly aggressive item, IMHO. Stock power cable, QED speaker cable of some multi-strand, flat format. And my room is about 12' x 23' x 9' ht, so not dramatically different from yours in dimension. I did hear the 20.23at a store, but with tube amps only, and I did not find them bright.

One aspect of the Devialet, in my opinion, is that it really reproduces the source material as it is. My Naim was not as accurate in this respect and so there was more 'sameness' to the sounds it produced, and less of the actual recording. That said, not everything sounds good with either system. Recordings with crappy miking, mixing or mastering (or whatever flaw) sound like crap. If the 400 is better than the 200, I doubt one of the benefits would be a less revealing sound.

An interesting experiment might be to try some acoustic treatments, even very crude pieces of foam, for an afternoon just to see if it makes a difference to the sound