I will echo the other comments regarding source: you can’t replace information that was never there to begin with, and investing in a good source will let you hear all future upgrades. Luckily, there are some truly great streamers, turntables, CD players, etc, for ‘reasonable’ money -personally I love the ND5XS2, but I don’t have the same resources of some of the folks on the forum
In all honesty, I do think there is a significant drop in the improvement to price ratio once you get past around $5000CAD in sources. The old rule of thumb was 2X the cost for a substantial lift in performance, and for me, $10K is a bit too much to spend on a source. YMMV.
That said, I listened to the SN3 and the XS3 back to back with the same source and speakers, and I was genuinely surprised at the difference the SN3 bought to the party. Everything felt bigger, more real, more dynamic, and more alive. I realize you’re talking about the XS2, which I’ve also listened to extensively. I found the XS2 to be extremely good, but it lacked a certain vitality, favouring an ever so slightly smoother presentation. The SN3 by comparison feels less filtered somehow, a bit more raw, but also feels more vital, bigger, and faster. For what it’s worth, the source was the ND5XS2 for that audition: it was good with the XS3, but it was great with the SN3.
If you’ve got a good price on the SN3, I wouldn’t hesitate; it’s a giant killer if you ask me, and real value for money, even at full price. I think there’s a bit of dark magic going on with the SN3, it seems to manifest an uncommon life and energy to the music that I’ve not heard since listening to a fully active olive system back in the day.
I don’t have much experience with the ProAc’s, but I’ve used exclusively monitor speakers and naim equipment for 25 years, thus I’m familiar with small speakers that crave power. Naim amps have always delivered plenty of grip and control, so I’d expect the SN3 to only improve on the XS2 in those terms with your tablettes.
Searching for general info on the SN3 across this forum will reveal a great deal of positive feedback as well, I sincerely doubt you’ll regret making the move.