Mr. Big,
Your method is kind of what I followed. I've been engaged in this passionate pursuit for over 40 years, been to 20 shows, read hundreds of reviews, visited numerous retail outlets to listen (when they existed), etc., so I think (hope) that by now I know how to listen to kit (albeit I'm always looking to learn). However, we may differ on the methodology where you suggest, if I understand you correctly, that I switch class d kit for tubes and back/forth. That's simply not practical and, perhaps, not valid inasmuch as it cannot be done quickly, i.e., nearly instantaneously. Switching cables is no big deal but, at a minimum, you would have to wait for tube gear to warm up which means you're waiting minutes at least (in my situation). What I've done and reported here is to listen to tube gear, for over 35 years, and compare my aural memories of tunes I'm intimate with and compare to the class d presentations. Not scientific I admit. But I do listen "intently" and look for specific sonic attributes: soundstage, dynamics, bass, transparency, etc. So I think we're mostly in agreement.
After considering specific sonic attributes I'm trying to apprehend a holistic sense of the relative presentations. Most importantly, all of this in the context that, if my comments pique interest, you may engage a 15-day trial period. After comparing the Orchard Audio Starkrimon monos with the Class D Audio MiniGan 5's, I have decided to keep the Class D Audio monos. They continue to satisfy mightily. Mr. Big's comments re: class d having good bass and clarity but missing, perhaps, midrange presence were more evident, in my system to my ears, with the Orchard Audio Starkrimsons. Leo's products are beautifully executed and certainly deserve a listen. Orchard Audio offers a trial period as well but with a restocking fee. Ultimately, to my ears, the Class D Audio monos provide a noticeably more fleshed out midrange and a more dynamic and present bass without any discernable loss of their amazing detail/transparency in comparison the Starkrimsons (which also exhibit astonishing transparency and detail). Indeed, concerning the Starkrimsons, Leo graciously noted,
"No problem with the return. Many of my customers have this kind of feedback and opt to use a tube preamp to still have the prominent second harmonic..."
I did use a tube preamp but in my system the "leanness" (which Mr. Big has previously referenced) was not ameliorated which does not mean the Starkrimsons wouldn't be the more musical choice in your system. However, for the reasons noted, I am returning the Orchard Audio monos and keeping the Class D Audio monos. I'm also keeping my tube monos. But both upstairs and downstairs I'm listening to GanFets. No desire to change out. The tell. It's been a nice ride all.