Bose A20 upgrade from DC13.4 passive- no audio

I’ve been flying my RV7A for 10 years with a DC13.4 passive headset running through the built-in intercom on the garmin SL40. Alas, upgraded to Bose A20 and took a flight earlier today. The FBO reported that they heard my transmission, however I was not hearing any audio. If I pulled the larger audio plug out slightly, I could then hear radio chatter on Unicom but accompanied with squeal.
I see that the smaller mic plug for both the DC and Bose are similar. But the larger audio plugs are different (one ‘stripe’ on the DC and two on the Bose). Was told my DC plug is mono whereas the Bose is stereo?? The switch beneath the batteries on the A20 is set for mono.
Do I need a different jack for the audio plug to accommodate the Bose?
Any thoughts welcome
Jim Diehl 7A
Lock Haven, Pa

Should not need a different jack.

A lot of new headsets are set up for STEREO or MONO. Most of our airplanes (older ones any way) are setup with mono audio so the newer headsets with an extra ring for the extra auto channel goes unused.

The bad thing about the stereo plug going into a mono jack can have poor or missing connection for the audio going into the headset. I have seen poor quality jacks not align with the correct ring on stereo headsets plug. That may or may not be your issue.

Also, most new headsets that can be used as stereo have a switch to set for mono or stereo.

I am sure someone with more knowledge than I will be along with more info.

I had almost the same issue. If you get audio by pulling the plug out one notch you need to rewire the headset jack if it's only mono or replace with a stereo jack.

I dont remember exactly but I think the bose only listens to the left channel in mono and if your hearing audio when you pull the plug slightly thats more than likely the problem.

It took me a while to figure it out because I followed a stein video wiring my headset jacks which turned out to be a mistake because it was backward for my setup.

Update

Thanks guys for your suggestions. Both were helpful. The installed left/right jacks have three terminals with one going to ground. In the end, and after some local discussion, I installed a jumper wire (non-shielded) between the other two terminals. I now have audio with the Bose A20’s and all works well.
However, when I transmit, I’m getting a mild single electrical clicking sound at the beginning of when I first speak. The click does not occur when I speak through the internal SL40 intercom, only while transmitting.
I’m thinking that I may be getting some electrical interference . Perhaps the jumper should be shielded?
Again, thanks for the comments.

Jim Diehl 7A
Lock Haven, Pa
Dues paid