Well, don’t think about the two voices coming from the one “output” as a stereo output. Think of them as two mono outputs. This is only done to save space and therefore cost. The “tip” and the “ring” of a TRS cable allow you to send two mono signals over one cable. A TRS Y cable allows you to split the tip and ring into two TS cables (ts cables only allow one channel, ie mono).
So through all of this, you are actually keeping each track source (BD, BT, etc…) on it’s very own channel. What you are talking about doing is merging two channels into one channel. Other than some fancy expensive cables that probably do exist but I’m not aware of, the only way to merge two channels into one is with a mixing device.
If your Presonus console’s input is indeed a mono input (i.e. one channel) then you will need a mixer to mix the two RYTM channels back to one before going to it. If the console’s input is actually a TRS input (sometimes called balanced although that has to do more with “ground” then stereo) you could connect it directly. The problem there is if that input doesn’t allow you to pan (L/R) each track individually, then you wind up with the BT panned hard left and the BT hard right. It’s possible to use software to fix this (Ableton allows you to select one channel from a stereo input and use it like a mono with panning).
Unless you are short of inputs on the Presonus, I would use a TRS y cable to split the two tracks into separate mono cables, then plug each one into it’s own mono input on the presonus.
That is by far the simplest way to accomplish what you want. If you don’t have enough inputs on the Presonus, you will need a “pre” mixer or simply an Input expansion (not sure if Presonus has adat, spdif expansions or not) or just another interface with more inputs.
Good luck!
