I got the S17 Pro early this afternoon and, after letting it warm up for 35 minutes to just over 50°C, I've been listening for about three hours. There are a number of differences, mostly rather subtle, from the Liquid Platinum and I am very happy thus far. As I hoped, it does add a little warmth (not a lot, but a welcome smidge) to the Arya Sealth, bass seems to be a little more prominent in the mix, and everything seems to hit a little harder. The biggest difference, which was almost startling at first, was that the soundstage was not only more holographic, but it was immediately in my face; the LP soundstage was placed more in front of me by a couple of rows.
As I suspected, the volume issue is a non-issue for me. The Arya Stealth is the only full size headphone I've tried this far and I got plenty of volume around 35 in high gain or 42 in low gain. I did listen to one album with the Thieaudio Monarch Mk II, which is more sensitive than any of my full size headphones, but is not particularly sensitive for an IEM. It was nice and loud at 32 in low gain. BTW, the temperature, which had risen to 64° actually dropped a couple of degrees while listening with the Monarch.
Finally, the S17 is really on the large size for a desktop unit (I was well aware of the dimensions, but seeing it in the flesh is a bit different). It overhangs the Denafrips Ares 12th-1, which is no compact unit, by a goodly amount on each side, although the Ares is slightly deeper. I wouldn't like to stack the S17 right on the Ares with the short stock feet due to the heat. I ordered the tallest conical adhesive rubber feet I could find on Amazon (.89 inches) which give quite a bit of clearance for heat dissipation, hopefully enough.