To join the ongoing Yinman 600 discussion, I will share my experience:
I have been using earbuds in Shanling's office for some time now, a fairly well-regarded model from one of our competitors. But it was missing a bit on technical performance, so I spent way too much time in this thread and finally two weeks ago I ordered the Yinman 600. Directly from their Taobao, it seems they are just on the opposite end of the city from us
They are great! A massive upgrade from my previous earbuds.
For source matching, at first I tried it with a few of our UA and H models, and settled on Shanling H5 (5.6V @ 300 Ohm / 840mW @ 32 Ohm), which seemed like the first device when they felt properly powered. Later I upgraded to the Onix XP1 with external power ( 12V @ 300 Ohm / 2400mW @ 32 Ohm), it might be an overkill for these simple earbuds, but they sound simply lovely with it and it's now my main office rig.
I might later give it a go with our T35, which pumps like 7W into 32Ohm
Thanks to all of you in this thread for keeping this small niche of Hi-Fi going and sharing all the hard-to-find info.

To continue on my path of properly powering
Yinman 600 Ohm, I now switched to the Shanling EH2 - 4.4 W @ 32 Ohm / 710 mW@ 300 Ohm (Sadly don't have specs to 600 Ohm)
- Frankie Shanling