Hi TFi - welcome!
The quickest way to achieve what you want would be to set-up the TTS-1 like the other posters said, then you right click in the MIDI track header area and
Freeze > Freeze Synth. This will create an audio copy of the MIDI part and disable playback of the MIDI. This also frees up the resource used by the synth during playback.
Let us know if that accomplishes what you wanted.
Cheers