It can be done however its not the preferred method of connection as the headphone jack is already amplified. You would want to start with the volume control of the phono/stereo system set very low to avoid blowing up the second amplifier/speaker setup.

The phono probably has jacks on it already plugged internally into your stereo. If you open the unit you could take those outputs and plug them into the phono input on a different stereo.

The phono signal also is quite low-level. It's quite likely you'll hear a lot of hiss when you turn up the volume. If you don't plan to use the tape deck at all, you'd be better off taking that output and feeding that into an external amp. Are there any "tape out" jacks on the back of this unit? Those would be easiest to use.

Steve - there is a DIN socket on the rear of the unit that I thought was for an external amplifier, but is probably for input only, as I was not able to use it for connecting to the amp.

Cseyer, that sounds scary. I definitely don't want to risk blowing the amp.

Oh, well. I will probably just scrap the thing and try to get a turntable I can use. Much less fuss.