Replacing Radio - Ground Problems?

[68Glbtrotter]

1988 Excella
I am replacing a defective radio with a Pioneer AM/FM/CD player. The Pioneer has the memory wire, i will hook it up to power and install a switch to cut off the constant battery drain.
My problem: when I use an external power source (a bench technician's 12v Power supply) everything works great! When I hook up to my AS blue (+) and white (-) everything works on the radio (even the remote) except no audio from any speaker.
I do not have chassis grounded (although I've tried it)...The radio's black wire is connected to AS white (Grd); radio's constant power(memory) and ACC power is hooked up to AS blue wire (12V). Both of these 'AS' wires supplied previous' radio power.
Old technician is stumped!

Danny

[Skater]

If the radio itself is working, I suspect a problem in the speaker wiring. Does the Airstream have a common ground wire - that is, are all of the speakers' grounds tied together? My memory is hazy but I believe current head units do not like that. Easiest way to check would be looking for continuity between the different speakers' negative wires.

Or try just hooking up one speaker and seeing if it works.

[68Glbtrotter]

Yes sir,
The radio is working and as long as I use an external power supply all 4 spkrs work. It is just when I hook up to AS power it knocks the sound off but it still lights up. Grounding through the speakers may be a culprit because..when I was taking it to my camp, I remembered I left my Elmore James CD in so I just hooked up + power first with no ground wire (I know bad practice) and the radio lit up I was able to eject CD and still had not hooked up what I think is the 12V grd.
I took the trailer to my camp and that is where it is now so I'm heading there this weekend to check further.
PS All four spkrs read 4 ohms but I did not check for common ground although the speaker I pulled out looked like it was not grounded 'commonly'.

Sorry for long wordy posts -