I think you already know my story, where a dealer loaned me an XLS-DR to put on my NDX2, and my wife was impressed enough she contributed a 1/3 of the cost to buy it.
Can I put that improvement into a percentage? I don’t know, but it’s not just 10% or 20%. It might very well be 30% or even a lot more. It’s been so long since we compared.
Actually, that does ring a bell - esp with how your wife was genuinely sold on what she was hearing!
Dan
And when I brought in a 555 PSDR to audition against the XPS DR we had on the NDX 2, the first thing my wife did, knowing the cost of the 555, was put her head in her hands and moan, “Take it back. . .” Of course we didn’t.
Not sure how to put it in percentages, but most agree the 555 is a very substantial upgrade to the NDX 2. Another 30%? 40%? Just more of everything.
I can only rate the impact on my 272 (on a 300 DR), moving from the XPS DR to 555 DR. Not looking at the numbers themselves, assuming the XPS DR brought a 15-20% positive impact, the 555 DR brought a 40-50%. I’d say more than double the impact of the 555 vs the XPS, only wished I’d gone straight for the 555 from the very beginning: refinement, bass definition, image size and depth, realism. No contest, 555 is the one to get for max performance.
Just found and read your recent post, with a question…
This might be a useful resource for you, or maybe just an entertaining read….
Long story short, having done the listening and learning, then waited and watched.
Eventually found a lovely 555PS DR, which suited our budget. Patience is maybe key.
Like my mum always used to say, “the best things…, come to those who wait”.
Good luck
R
Not a % but I’d say the XPSDR improvement is ‘appreciable’, the 555PS improvement is ‘transformational’ 
I recently added a XPSDR to my NDX2, it’s hard to put the improvement into percentages terms, but there was a definite uplift in sound. Yes, you get a more solid & tighter bass response, the music is more dynamic and better fills the room.
I purchased the XPS DR for what I think was a really good pice at £1,600, my system sounds really impressive and musical to my ears, but I can only imagine what the 555 would bring to the party, that next step would cost me nearly double the price of the XPSDR!
So I’ve jumped on an XPS DR - which only had one previous owner, and was around 6 years old. It’s in excellent condition, and I picked it up for a reasonable price. I’ll make sure to drop some initial notes and feelings on the 3 box setup I now own, once I’ve put some listening hours in. I did seriously consider adding a 555DR. But even previously loved models, were financially a little too rich for my taste - esp after the recent expense of purchasing the other two components.
A little off-topic, but does anyone in here bother utilizing System Automation? For the price of an inexpensive and readily available cable, I’m wondering whether it’s worth connecting my NDX 2 to my SN3 - so I can just use a single remote control?
Dan
To my own surprise I found SA actually super intuitive and useful. For volume control (and automatic input switching to the streamer) playing music from within the Focal/Naim app.
I hardly use the remote anymore, as my other main input is vinyl. Then I’m usually close to the amp anyway, or there’s no other need to turn the volume up or down.
For the trivial cost of any generic minijack>minijack cable you might as well just try it.
Exactly. Super easy to use.
I use SA with the NDX2 and my 252. Works well and is easy to setup.
What did you pay for your XPSDR? Maybe I need to adjust my thinking on worth?
With tax and delivery, it came in at $2260. 
I don’t bother with system automation. My preamp is close to the sofa so I just use the manual control. It’s one less cable to clutter up the back of the rack. I found controlling volume on a Classic preamp awkward with the app or remote so I’m glad I don’t need it.
That’s bad news for me. LOL
Congrats. That’s a great deal. Naim used prices in the U.S. are crashing, on the [soiled] coattails of FNA. 
Maybe try listing it on Canuck Audio mart JDP.
My dealer has a new one for $6999…Canadian 
.
Agreed @JosquinDesPrez you might get more looks on USAM. Did you move both sets of Fraim yet?
I was wondering if Naim’s decision to discontinue the XPS DR - by replacing it with the NPX300, has impacted prices? For example, I was reading that the XPS DR was originally $7499 new. Whereas now, you can pick up brand new models in the UK for £4500 - so roughly $6000. That’s a fairly significant drop off on new prices, which I guess has trickled down to 2nd-hand prices too.
I have a portion of his Fraim.
An XPSDR has been sitting unsold for 6+ months. The current price is $1,800. The market price on them has plummeted.
There is a guy on the Naim forum that bought the special cable to hook up his 555DR to his 333 streamer. I have not seen anyone doing that with an XPSDR. I wonder if it considered better than the NpX 300?