I also have a pa900 and i use a 90 degree adapter into the pa 900 and the transformer plugged into that. I seem to remember sam ash had a xlr to 1/4 in cable with a built in transformer a few years
ago. but i don't remember when i saw it. by the way i use the right angle 1/4" adapter so I don't damage the mic jack on the keyboard and it gives it some give if someone bumps into it.

Mel