stevem Messages: 4733 Registered: June 2004 Location: NY
Senior Member
They are made to feed other speaker cabinets that where offered back then and had power amps built in.
The point in these amps where they tap the signal off is the output side of the preamps and the input side of the power amp, hence the popping you where hearing when tapping the end of the cable !
If you ever have a amp the does not work doing this simple test will atleast confirm that the power amp section is working.