The circuit would have to be rebuilt in it’s input and output characteristics.
The simplest way would be to have transformers or active opamps on the input and output.
The circuit internal to the box is single ended, and it is of a equalization network, done electronically, in cascade, IIRC.
Making those circuits balanced is not really a functional way to go, so the core aspect would remain in unbalanced form.
It is only realistic to go balanced at it’s input and then it’s output be made balanced.
If that is indeed what you wish to do.
Applying this to a Kube, any Kube for any Kef speaker of that era, would be a full on audio engineering and guesswork job, with dubious quality of outcome, until it is assessed in the post fact condition.
The simplest way would be to have transformers or active opamps on the input and output.
The circuit internal to the box is single ended, and it is of a equalization network, done electronically, in cascade, IIRC.
Making those circuits balanced is not really a functional way to go, so the core aspect would remain in unbalanced form.
It is only realistic to go balanced at it’s input and then it’s output be made balanced.
If that is indeed what you wish to do.
Applying this to a Kube, any Kube for any Kef speaker of that era, would be a full on audio engineering and guesswork job, with dubious quality of outcome, until it is assessed in the post fact condition.