According to JPAC's website
"JAMMA cabinet speaker routed to screw connectors for wiring to powered sound card or hacked PC speakers."
http://ultimarc.com/jpac2.htmlThe speaker pins are used. So you are probably right.
Then do what krick posted aobut stereo-mono.
I wish there was a good way to go form mono to stereo that works with Y connectors...
OT cmment. I made a headphone amp for my bass guitar. But since the guitar is mono I made a mono amp. I just have a jumper going to both headphone speakers. I want to add a CD input but as it stands that would end up converting the CD to mono. Not bad for practicing I suppose.