Thanks for a clear and very straightforward answer.
I read about the Korean Bakoon yesterday but it lost my attention due to it being battery powerd ... in the long term these will need to be replaced.
I'm checking out the Japanese HDA-5210 atm but it might be discontinued, I guess in favor of the Korean one. Still, the Korean one might be a worthy alternative, it's from the same company after all. Thanks for pointing me there again.
I hadn't considered the Stratus yet, I somehow got the idea the Sonett 2 was better for sensitive phones. I see Donald recommends it for use with the TH-900 on the Stratus page. Great!
So, off to dig through a couple more threads!