timoc wrote:Thanks, I may have to do the latter, given I don't know how to make a load box.
It really doesn't need a 'load box'. The manual is quite explicit: the external speaker output doubles as a fully compatible unbalanced line-level output which can be connected to high-impedance line input and it will serve as a 'high fidelity' connection!
Think of it as a powerful mono headphone socket!
I think the manual states that if you've pushed the banana plug all the way in and still hear the original speaker, you can push a second plug into the left adjacent socket halfway to kill the speaker sound
Not quite. You need to (fully) insert both banana plugs to access the unbalanced output to feed an external speaker or line input. The right-hand socket is the ground reference (black plug in your converter lead) and the left-hand socket (red plug) carries the (hot) signal voltage.
Normally you would push both plugs all the way in, in which case a break contact on the left (hot) socket will disconnect and mute the internal speaker. However, if you want the internal speaker to continue working you can achieve that by pushing the left plug in only half way, since that will still pick up the signal but not activate the break contact.
What could go wrong with the method described by others of plugin in a banana - rca cable and turning up the volume slowly?
Assuming the machine appears to work normally on its own, I dont think anything can go wrong with deriving a line output in the manner described.