I bought a double keyboardstand from http://www.jaspers-alu.de/jaspers-alu/images/2K105not.jpg and I have a question.
I have a technics kn6500 and a yamaha psr9000 pro. (I'm a bit spoiled...I know)
I put the technics kn6500 on the buttom and the psr9000 pro on top.
I always play the keyboards sitting.
I only can play with sheet music...so I bought a musicholder. The one on the keyboardstand I bought is to close to my second keyboard.
The problem is the keyboards are so big....I have to put the musicholder on a very high position and when I play mostly after some time I have a pain in the neck.
Is there no other solution to this problem ?

Hi Alain!
Try lowering the bottom keyboard to the lowest comfortable spot, so that you can also lower the top one. Put them both in the flat, horizontal position. Place the music rack back on the top keyboard and use that. That's what I do. It works for me as long as there is no page turning required.
Tom G.

I'd adjust the music stand so it covers all but the KEYS on the top kb.
(You may have to move the arm to the front leg to do this)
That way, the music can be right in front of your face, and you can still play both boards.
I'd also put the Yammy on bottom for a few reasons:
1) It's bigger
2) It has no speakers, so the kn can be heard better - even with the 9k pumped INTO it.
3) I'd use the controls and styles of the Yamaha as the master, and just augment with the 6500. (personal taste)