Downward compatibility for ps 2 peripherals?

[Geoduck]

Just a simple, if silly, question:

Can you use a ps 2's dualshock 2 controller on a psx?

I was wondering, since I plan to reuse my old psx for psx games, to minimize wear and tear on my new ps 2 (they say it's bad for the machine's laser lens if you use it to play too many different formats too often).

Thanks

BTW, is the ps 2 game Oni in cd format? Some guy sold me a pirated copy of this game in a cd. There seems to be a humming sound coming from the ps 2 while I'm playing it. Could this be bad for the machine (although the ps 2 WAS designed to play cd's as well)?