Look at the latest Supplementary Manual for MODX.

Source - modx_en_sm_c0.pdf page 50:

Combine Songs, Patterns and Audio files within the Live Set display

Press the [LIVE SET] button, or touch the LIVE SET icon -> Select the User Bank -> [EDIT]
...
Slot Type
Indicates the selected slot type.
Settings: Perform (Performance), Song, Audio, Pattern

and (pg 51) ...

Playing back Songs, Patterns and Audio files from the Live Set display
Operation Press the [LIVE SET] button, or touch the LIVE SET icon -> Select the User Bank -> [>] (Play) button
NOTE When a Song or Pattern is playing back, you cannot change the Performance or the Slot. An error message appears when you try to
change it.
NOTE When a Song, Pattern or Audio file is playing back, you can open the corresponding playback display on the Performance by pressing
the [>] (Play) button.

There it is. Very Cool! I appreciate the pointer. Beats looking through 370 pages of manuals
and now I know what parts of the 2.5 update have new reference pages.

I was busy at work for a couple months there and just got time to get back on my new toy.

With the Jack audio system all 10 outputs and 4 inputs can be used under Linux with the following settings:
Sampling rate: 44100 (fixed)
Frames: 512 / 256 / 128 (the lower the better for latency)
Buffer: 3 / 2 (the lower the better for latency)

Midi works out of the box without Jack.

An easy way to get Jack running is to install Ubuntu Studio and follow these instructions:
https://help.ubuntu.com/community/UbuntuStudio/UbuntuStudioControls