Interesting. I take it you hooked up a 10V PSU or does this have a built in voltage regulator so that one can run a easy to find 12V PSU?
Wait now i am confused... do you need the external 10v when using a PWM?
There is no internal voltage regulation. Yes, you need a 10V regulated (or 9V regulated, they are more readily available) power supply. If you click on the link in the eBay auction, there is more information about them on that website, including how to wire them.
I use two of these dimmers (one for each color), each one is wired to two drivers (4 drivers total, 48 LEDs), and the dimmers are run off of one 10V regulated power supply.
I haven't measured the driver's current range with these dimmers but the LEDs cut out at what appears to be 30% or so. I'm not sure why but it seems to be common with the MeanWell P drivers and it doesn't bother me since I run mine at about 80%. Just an FYI.