Hopefully this post helps someone trying to find a power amp for their Kemper. Just wanted to post some results from a personal test comparing power amps.
Some friends had all of these amps in one spot so we tried various combinations to see what works best with Kemper. Test on various v30 cabs, mesa 2x12 and orange 2x12 mostly.
3rd place (distant 3rd): Crown XLI 800 (Solid state, Class AB): https://www.crownaudio.com/en/products/xli-800
Summary: Don't use Crown XLI series with Kemper, only use for PA/drums/bass/music. Sounded sterile, lacking detail, and "hi-fi" compared to Orange SS Class AB amp.
Was expecting better due to Class AB design, haven't compared directly to Crown Class D (XLI amps) yet.
2nd place: Orange Pedal Baby 100 (Solid State, Class AB): https://orangeamps.com/pedal-baby/
Summary: This is the winner overall (bang for buck). Sounds significantly better than Crown, much more 'guitar amp' like and warmer/less digital. Not as deep, transparent or 3D as Mesa.
1st Place: Mesa Mark V
(tube, inserted into FX return loop)
Summary: Tube is still king. 3D, transparent, deep and rich, darker and less 'boxy' than Orange - but not enough to require tubes. A $2500+ tube amp section is expected to sound better than a $400 solid state option - but not enough to bring on the road. In a live setting, the Orange SS option will sound indistinguishable to the audience.