Hi, HalfBaked:
From what I can see, TTS-1 is a more or less proprietary soft synth that comes with Cakewalk by Bandlab.
I used Cakewalk 20+ years ago when integrated audio was just starting to happen and soft synths were a thing of science fiction, so I'm not up on the latest versions.
However, TTS-1 seems to be a DXi only General Midi synth -- please, correct me, if I'm wrong. There are a lot of options to fill that need available including the free Synthfont (which Sherry on this forum uses extensively) and many other Google-able ones.
I wonder whether Notation Composer's built-in Notation Software Synth will do the job for you. You can load just about any Soundfont 2 set you like and play 16 channels back on it (depending on the power of your computer).
If you are really in need of TTS-1 specifically (special sounds or something like that), perhaps this page will help you get started.
https://www.soundonsound.com/techniq...ab-tts-1-synth
I hope that helps.
All the best,
David