[XCSSA] AC Adapter Question

[X-otic Computer Systems of San Antonio]

I have a charging cradle for my new wireless headphones that I want to get 
an AC adapter for.

Info on the cradle is:  110V/60Hz, 12V/200mA

I have an AC adapter: Input 120VAC/60Hz 9W

                                  Output 12VDC/500mA

Plugged in the AC adapter to the cradle. Connection fit perfectly. Dropped 
device in the cradle after removing the 9 volt battery that powers it 
without the adapter. Heard a pop and that smell. Disconnected from the AC 
imediately. Put the 9 volt back in. Everything appears to be working.

My question is. Does the Output on the adapter have to be 110V/60Hz, 
12V/200mA exactly?

What went wrong? To much voltage and/or micro amps?

Will just stick with the 9 volt but wanted to go with the adapter for better 
range/clarity.

Thanks Gene