i was buying from Shopee instead of from AliExpress, it looks like Shopee has their own sending and receiving warehouse from china and my country, so the shipment was really fast and didn't have to go through usual customs.
i immediately tested it with some of the most hissy IEMs when used with the older BT20S : multi BAs and Hybrids
here i tested the DM6 (which has crazy high noise floor with BT20S) and ZSX (low but noticeable noise)
I'm happy to report that even with the DM6, thry noise is barely heard.
they seems to tune the output to about the level of the older BT20, but with cleaner sounding amp than the previous version.
the highest impedanced detachable earphones i have is the old Svara L, which if I'm not mistaken would be 115 ohm. i can get regular listening level at about 75% volume, so still plenty of headroom for me personally.
what they improve for me are:
-nice soft and flexible earhooks, no more metal wires inside them. i even tried it just for laughs with my ER4XR, and it can work!
-the detachable connector is a nice feature. it got me thinking of just getting a good and light cable (a Linum, perhaps?) with a straight 2 pin connectors, and i can just use the BT20S Pro and that one cable interchangeably.
-the buttons now have a lighter pressure
-the case, while a bit bigger than the XM3 case, can also fit another set of IEM, a bit tight and require a bit of management, but definitely possible
the only cons for me is the lack of volume controls, but otherwise I'd say this is a solid and satisfying product.
now it's time to order some more connectors!