I've got both, 9.7" & 10.5" - both LTE models
9.7" is in the Apple silicon back case, Smart Cover
10.5" is naked on back, Smart Cover on front
I've also got the AirPods and the OP's correct about the linearity of the volume control on the new iPads. Lower is much lower but significantly easier than the 9.7" to find a lower dB level so as not to disturb those around you. Same on AirPods, as I'm able to much more easily control lower volume output (10.5") than the iPad 9.7"
I've also found the 10.5" to be louder at its '10' mark than its smaller sibling, as well, with what seems to be less distortion and more of a low end/octave presence which in effect, rounds out the sound on the larger model to be more 'full' than the more treble heavy 9.7" ... and being lower frequencies take more power to present than mids and highs - I think the sonic signature of the 10.5" model is a feature... someone mentioned above ...as you have more control on the low volume registers and better, fuller sound than the earlier, smaller Pros.
Just MHO. I am an audio engineer and have several dB meters, if I remember I'll take readings this weekend of the 9.7", 10.5" and 12.9" (1st gen) iPads and report their results - w/video if possible. I've found the same with the 10.5" as I did with the original 12.9" models... with the USB 3.0 protocol, and the power delivery back to the dongle.. the iPad to camera 'connection dongle' with USB feminine to plug cam in to offload pics also works both with external DACs and mics.
The DAC is used to completely isolate any internal noise within the iPad - w/bit perfect stream of audio that's decoded from digital to analog externally. Allowing you to hook into sound rigs and 'pro' rigs for live events and source/recording on the iPads. We've completely lost the iMacs and MacBook Pros of yesterday and replaced with the original 12:9" iPads. I've got four more of the new ones on order for the same duties but they're not here yet
More resilient, always connected and phenomenal energy storage vs the laptops and, obviously, the iMacs. They're also well supported with software/apps in my industry, giving us a larger, more reliable and easier to use toolbox than any time in history ...I've been doing sound, live and in studio for three decades.
Gone the days you had to say 'we don't have that song'... as you've got em all on some pound device that lasts 10 hours off 110v! The ability to 'mix' or EQ the venue via wifi or Bluetooth and and iPad -- allows me to walk the venue and set RTA mics anywhere for analysis and the best sound for that area.
It's unbelievable how far we've come and I, for one, am very happy to see the headphone jacks go, and the USB C/Lightning External DACs being supported and providing significantly better sound - as for the quad speaker systems in the three iPads - they're all fantastic compared with older, two speaker models. Just as the iPhone 7's dual speaker changes the iPhone, so does the iPad's 4-speaker implementation.
And no, Apple didn't 'skimp' on their iPads this time around. Not on any corners or components. They've aced the tablet with these guys.