You are absolutely right. These remain my favorite "store bought" buds. We shall have to see, with the next new models, whether the lesser impedance buds will sound as good, or even close to the 2.0 600s.I know a few earbud enthusiasts who skipped out on the Yinman 600s due to the crazy driving requirements.
Some of them only use a small dongle + smartphone and went for easier to drive gear. If there were a earbud that sounded similar to the Yinman 600 without needing the wicked amplification demands, that would be the killer.
And, while they are commercially available, the @FranQL made Caelum are very similar in sound, though much much easier to drive.

I would be interested in hearing your power experimentations with this bud.In longer have the DX320/AMP12 but the MAX Ti has more driving power and a better amp section. Nonetheless, I will add the MASS-kobo 475 to the chain. I also will receive the RA2B-FE soon which is designed to drive demanding earbuds. If they can take up to 10w of power, I might consider buying the Defiant too. I love these earbuds from the first very listening, I really wasn't expecting it.
I am planning on getting the iFi Pro iCan Signature in the future (especially for head gear like this), but for now other things draw my attention and money away from pulling the trigger on this.