I have 252/SCDR/250DR and 282/HCDR/250.2 systems in regular use in different rooms. I also tried the NAPs on each of the other pre-amps when the 252 arrived.
In my view and with my rooms/ears/speakers/music preferences, the 250.2 and 250DR are not identical, but closely related cousins that each have their benefits and shortcomings. Albeit, those differences are not huge.
Bear in mind that non-DR equipment did not suddenly break when DR was launched. A recently serviced 250.2 is still a great power amp and I will keep mine, at least until a 300DR can be tried and found to be better in my room and with my speakers, etc.
I went from 282/SC to 252/SC then finally to 552. the 252 in hindisght was a step i could have easily skipped. Fine though the 252 is I really did love the excitment of the 282 and i still rate it highly. The 552 was excitment and refinement combined. Sell the CDX2, your sorces deserve the best pre imho an ex dem 552 would (was) my go to. Never looked back
This is slightly off topic, but might be interesting (for discussion purposes at least).
Prerequisites: I have never thoroughly demoed the 282. Speakers are Dynaudio Contour 60
I recently went from 272/555PS+300DR to NDX2/555PS/252/SC(nonDR)+300DR. I still have all components, so I am testing a bit back and forth.
I find that the NDX2 gives a lot more texture, and refinement i bass (especially) than the 272. (Still with 272 as preamp).
When I also switch from 272/555 to the 252/SC it becomes a lot more refined. Even more texture is added, and it simply sounds more like music. Difficult to explain but the music is calmer, bigger and more detailed.
(And here is the tricky part:)
At the same time, when turning up the volume some music gets a bit more tiresome. As if it is too much (espesially on the top frequenzies). I feel like the 252 ultimatly makes me turn down the colume a bit - but I really cannot compare as the volume controls are very different. I actually wonder if this is fooling me - that I am actually playing much louder on the 252, but feeling it is lower as it has more control - therefore turning it even more up - and then it gets unpleasant. Does this makes sense?
For referance (even tough I do not know if this really desribes anything):
The 272 was locket at maximum volume of 54 (some music could be tiresome over 50 but never unpleasant)
On the 252 I really cannot go past 9 o.clock - 10 is mostly unpleasant.
I considered demoing a 282 - but gived all descitptions of it beeing more forwardā¦ well, I cant have it more forward or brighter than I currently am.
Linn and Naim said 40 years source first, but thereās been a lot of innovation in speakers in the last 40 yearsā¦ I donāt think speakers last is still applicable.
Better amplifiers have less distortion so tend to be more comfortable to listen to at higher volumes. I have certainly noticed this over the years. Perhaps with the 252 you are now putting too much energy into the room? You could try a SP meter at your listening position to check?
Not sure about others but I associate bright with more treble, and forward as the sound stage is pushed forward towards you or more in your face. But we all describe things a little different so thatās what makes this fun and part of the musical journey!
Iām a little confused. If you turn up the volume and it sounds tiresome, that suggests higher listening fatigue. There are several factors that contribute to listening fatigue but I wonāt go into that.
In your case, the 252/SC is said to sound calmer and more detailed than 272/555. However, the 252/SC is causing you to turn down the volume more than the 272/555. I thought it should be the other way round. I think the key is to try and listen at an almost same volume with both amps(although this is rather impossible to do accurately) and see which one gives higher listening fatigue.
In my experience, improved detail does not contribute to listening fatigue. A forward sound, harsh or bright treble and prominent midbass or upper bass which sticks out more than the rest will cause listening fatigue.
If you have a smart phone, just download a sound meter app (should be some free ones). May not be perfectly accurate but it will do the trick to compare the listening levels on one setup vs the other.
Interestingly Iām finding that with a 252 on my system I dont feel the need to play it so loud.
My wife has commented that Iām not playing it as loud as I normally do. The 252 seems better at lower volumes than the 282.
The 282 is good and can be improved with SC/SCDR etc
The 252 is better, but in my experience, it never provided a really significant improvement over the 282.
The 552 is in a different league, even with a Non-DR power supply.
The rest of your system will easily support and integrate with a 552. Of course, a 500 power amp will deliver more of what the 552 can supply. I would also leapfrog the 300 if/when you consider a power amp upgrade.
But sticking with your initial post, and re-iterating my opinion above ā¦ Option 3 ie 552/Non-DR.
Anyone buying a 552 hoping that it and the rest of the system will sound like the real thing, especially if we are talking live acoustic performance, is likely to be disappointed. The 552 is a very good amp with a good balance of trade-offs that presents a good āliveā sound compared to the 252, which is a much smoother and more refined performer than the 282, but fails to capture certain guttural instrumental tones, although it achieves a good balance with the piano. Thatās my take anyway. None of them are perfect. But then neither are many live performances, whether itās an off-night for some or all of the performers, poor auditorium acoustics or whatever.
Clive, you get full VIP- tickets to any musical event at your leisure. Youāll be placed in a equilateral triangle position in front of the band in a private enclosure with full hospitality, back stage access after the venue with free champagne bar, sweaty hugs from the musicians, signed T-shirts and of course ācoke anyoneā? Enjoy Peter
an ex dem 552 would (was) my go to. Never looked back 
Enjoy Peter