Extra outputs on a Joule LA 100 MK III?

Use that second set of outputs for a pair Subs or powered bass sections of hybrid speakers (Martin Logans or Vandersteen 5a's); or for Bi-amping...

There is a set of tape outputs.
Looking at the rear of the pre-amp, starting at the outputs, left to right there is:
Tape Out - output 1 - output 2 - the mystery output.

Many pre amps/line stages include a tape loop. They will usually have jacks for Tape In and Tape Out on the rear. The Joule uses an isolated switching design for a tape loop and your second pair of jacks may be considered the same as Tape Out.

So long as there is not an impedance matching issue, they could also be utilized for a powered subwoofer or bi-amplification.

Try sending an Email to Joule. You should receive an answer with more details on your questions.

If they are closer together than the rest and next to the phono imputs I think they are for cart loading other than the provided 47k ohms.

I thought they were imputs sorry!!!

If they are closer together than the rest and next to the phono imputs I think they are for cart loading other than the provided 47k ohms.

They could be buffered tape output jacks?