Hey Lon, congrats on your new Mapleshade furniture. You've been lusting after this rack for some time now, good for you! Now you have the complete sets you wanted, plus the added sonic benefits.
It's amazing indeed how much better the Mini Torii can sound once you start dialing-in the right tubes to suit for particular conditions. In my case, I get significantly more detail retrieval and transparency now, something I did not believe possible a few weeks ago. I need to thank Les Lammers for his right-on inputs in this topic.
You may be right about the burning times involved, as these 12AT7 Brimars are coming around, but very slowly. In any case, the sound has improved so much now I don't mind waiting indefinitely while I enjoy the music.
I think the combination of DM945's and OA3's in the Mini may not be ideal, as those speakers tend towards the warm side of the spectrum, and the OA3's have a powerful low-frequency presence in the Mini. In my opinion, some sound details were lost behind the low frequency wave generated in the heavier bass passages, rendering the sound too dark to discern those details.
One can go to the extremes (from OA3 to OD3) and still get a much preferred result, as I am enjoying. This is why I guess an OC3 may be just the ticket for the ideal tradeoff there, although I'm not at all in a hurry to try it, as the sound now is just better than ever.
I reckon it is true also, as you point out, that these amplifiers are constantly improving with age. I know mine keeps doing so. After all, it is just 8 months old and I guess prone to get even better over time. By the time my Mini yields its best sound plateau, the final tube complement selection in my Mini will also be quite settled, and I expect a definitely synergistic higher sonic level then.
It's been so much fun, I don't care tube rolling and critically listening for a bit longer now, as the results seem really worth it.