Currently the only way I've been able to hear anything is when I plug my headphones into the TX81Z. I have tried various ways of connecting through loopmidi and MIDI USB Interface but have been unable to get any sounds when I plug into my laptop. I know I'm missing something, but so far I can't come up with the answer.
You will not get any sound through MIDI cables or connections.
I'm assuming that you do not have an audio interface, right?
If not you need to take the audio out on the TX and plug it into the mic in on your laptop. This is not the optimum way of recording as an audio interface will give you a much cleaner sound.
For stereo you would plug the two 1/4" plugs into the TX's I/MIX and II inputs and the other end into your laptop:
https://www.amazon.com/xlr-male-1-4-adapter/s?k=xlr+male+to+1%2F4+adapter&i=electronics-accessories&rh=n%3A172282%2Cn%3A3224439011&dc&page=3&qid=1561661188&rnid=2941120011&ref=sr_pg_3
For mono you would plug the 1/4" plug into the TX's I/MIX input and the other end into your laptop.
https://www.amazon.com/Hosa-CMP-310-Mono-Interconnect-Cable/dp/B000068O3I/ref=sr_1_3?hvadid=78546432118271&hvbmt=bb&hvdev=c&hvqmt=b&keywords=1%2F4+to+1%2F8+cable+mono&qid=1561661367&s=gateway&sr=8-3
Note if you have an audio interface the above is the same with the only difference being replacing the laptop mic plug with either 1/4" plugs or XLR plugs, depending on what you audio interface with except.
Just remember no sound goes through MIDI cables, just data that a synth or computer can use.