ATC 40a seems a good idea. However if you sell your Sopra 2 and 300 dr, you will perhaps have 11/12 k. The 40a are 8k. So not much money gained but 2 boxes less. However a downsize in sound i feel.
Ndx2/ SN3 and harbeth sl5 plus would give you more cash and space.
Less dynamics, scale, bass, but very musical system.
The 1s won’t appeal as much to cats as the 2s and can help free a bit of ££ …
Personally, I couldn’t live with these grilles, but at least they’d be cat proof.
The scratching post idea would be worth trying. Put it near where the speakers will go before you instal the speakers, and encourage them to use it. Our cats love them.
Gretchenfrage – is it about money or space? I don’t know much about cats – I am a dog person… But cat owners appear to suggest that cats don’t really care about Focal speakers. I can’t blame them (the cats, I mean) – I am not much into French manufactured goods either… With the exception of our coastal blue LeCreseut shallow casserole, and our “big” LeCreuset pot for curries… 
rat poison?
Get a dog,
Actually I love cats too but couldn’t resist.
No, 40As are 6.8k new. And not a downsize in sound to my ears, but then I’ve never clicked with the Sopras. Certainly, with NDX2/552 front end, in a different league to SN/Harbeth IMHO.
However, perhaps not too well protected against kitty claws. So, if actives appeal, ATC SCM 20As might be worth an audition. Functional looking but, on tallish stands, should be proof against feline attack.
Roger
i feel that 552/40a would be a little downsize vs 552/ 300 dr/ Sopra 2. But i have not compared…
SN3/ ndx2/ harbeth sl5 are indeed in another league, but the goal here is to gain some money too. So it’s not easy.
Are you not located in Canada Zipperhead banjo? I have a pair of Dynaudio XD 600’s that would plug directly into your NDX2 (digital out). I want to move them on because I now live in an apartment building, and can not use them to their full extent any more, they will play loud, and down to 20HZ. I am in Windsor, I would make a deal for your 300DR, but I don’t want to break forum rules in any way. Look them up, see what you think of them. They also have analog inputs, but that gets converted to digital, I use the analog inputs for home theatre, sounds fantastic.
Ditto (big floorstanders with full-length fabric grille cloth).
But if worried, some speakers like ATC have metal grilles. In that size room you may struggle to get any decent bass with standmounts (unless by standmounts you include PMC’s superb MB2)
So just to be clear… you are suggesting I downsize by removing zero black boxes, and adding one big and expensive one 
Sounds like a dealer 
The cat discussion appears to be have struck a chord. I’ve had cats in my previous life (pre-divorce)… and I agree… the cats may very well just ignore the speakers. I’m just not sure I want to take them in the house and take the risk. If the cats do gravitate to them, they could devalue their re-sale or just make it much harder to find a buyer.
Got one already
Buy secondhand ones, then you won’t need to worry so much - preferably already cat-scratched, or with child-defaced or whatever.
Caveat: never had Naim separates and never climbed to 552 level, so no idea how you’d cope with feelings of loss…
But the Nova, oft praised although not ever given the long term love fest treatment some other gear gets here, is a great way to spend your music time. I have Kudos S10s with my Nova, and like it very much, so trialing their new hip kid 505 successors as NigelB suggests is likely a great way to spend a day or a week or whatever. Going all in on the downsize will maximize your cash return and your space optimization. You’ll have a huge lifestyle adjustment as it is, and there’s also something to be said for choosing a system in the central space of the house that everyone can turn on and enjoy from their phone (that has happened here in stages).
Maybe keep the RP10 and see how you get on with it and the Nova - the digital conversion / restoration is very high res and tightly matched (although again, caveat, I don’t run a TT), but maybe it ends up in storage for a while before you can be sure you’re living in a no-LP world. The change you’re jumping into is huge, go gently.
For that matter, the 552 could also live in its box until you’re sure there won’t be remorse, generating extra funds later when you’re settled in your new home and family context, or popping back front and centre in a new system. Since funds generation isn’t the principal / exclusive motivation, I’d think about downsizing in stages, just as carefully as most posters here upgrade in stepwise but deliberate fashion.
I’m in Canada too, Ottawa if you’re nearby…
My sincere congratulations and best wishes to you and yours.
Regards alan
downsizing the bank account 
My experience with cats is grilles have too much elasticity for cats to enjoy getting claws in. But standmounds… I’ve seen no end of them getting knocked off stands by leaping cats.
