Unfair Competition: Orchard Audio Bosc Monoblocks vs. Pass Labs XA30.8

After hearing a friend's Orchard Audio Starkrimson Integrated Amplifier in my system (https://systems.audiogon.com/systems/9074) a few weeks ago (it sounded pretty good!), I arranged to audition a pair of used Bosc $1500 monoblocks (now called Starkrimson) for close listening.  Was curious to see just how well this "distortion-free" class D amp (https://www.audiosciencereview.com/forum/index.php?attachments/orchard-audio-bosc-pdf.47492/) could replicate my beloved Pass labs class A beast costing >$6000 new.  Close listening was done after several days of casual listening/break-in.

Bosc - The Good:
- Wide and tall soundstage
- Convincing central image
- Extremely quiet -- less baseline hiss than the Pass
- Fast transients
- Excellent instrument decay/echo
- Obviously more energy and space efficient

Bosc - The Not as Good
- Lacked soundstage depth/separation
- Less vibrant and engaging, lacking difficult-to-articulate "magic" of the Pass
- Inconsistent bass performance, some tracks sounded firmer and tighter, others weaker than the Pass
- "Flat sounding" with less fleshed-out midrange

After having the Bosc in my system for a few days and listening to nothing but that with a variety of music, I would have been very happy to keep it for the long-term.  It was only after A/B with my Pass that I realized what I was missing.  

Not a fair comparison dollar-wise, but I was, perhaps naively, prepared to be convinced the Bosc could go head to head.  A nice reminder of what I enjoy about the Pass in my system, though.  How to measure these qualities, though?