I'm going to go out on a limb here and say that the SA6 Ultra's tuning and feedback in going to serve as a baseline for a higher end model in the studio line.
I would not be surprised if a SA8 would be released next year with the SA6 Ultra's tuning but slightly better as they have 2 extra BA's to use where necessary to improve it even further. So I do think we're going to see the tuning from the SA6 Ultra from Dunu again, just not on a SA6.
But we might have to wait a while for it, seeing as the SA4 still has not seen a world wide release more than half a year after the domestic release and almost a year after it was announced. Apparently due to getting a re-tune for the western market, but I don't know anymore if this was confirmed or just speculation. It's available on
AliExpress from some reputable stores now so I guess it's had a soft release of what has been confirmed to be the domestic version, but it's not on the official store yet. Then again neither is the SA3 for some reason.
Might pick the SA4 up during 11.11 though as it does seem like a good IEM.
But there are almost no reviews on it and I do have the SA6 Ultra coming which might make the SA4 redundant. And it's coming very soon having landed yesterday.
I don't really mean to hound you for answers on the SA4 @Sebastien Chiu. I'm just eagerly awaiting it's official release and any info on it as I'm genuinely interested in the SA4.