I am not sure what you need and how much you understand about MIDI and audio, but I’ll give it a go:
EACH MIDI Track can only be set to one MIDI Port (Output Routing) and one MIDI Channel.
MANY MIDI Tracks can be set to the same MIDI Port and/or MIDI Channel.
So say you have 10 MIDI Tracks all playing to the MIDI Port “Microsoft GS Wavetable SW Synth” and MIDI Channels 1-10. These play through the computer speaker because that particular synth is part of Windows. You could now copy the 10 MIDI Tracks so that you end up with 20 MIDI Tracks. Change the MIDI Port on all the copied tracks to “UM1”. Now if you press play, you will hear both synths. The original set of 10 tracks will output audio through the laptop speakers, and the copied 10 tracks will output audio from the synth you have the UM1 connected to.
I cannot comment on the particular hardware suggested to you, but the right type of hardware (call it “X”) would enable you to route the audio from the 10 original tracks AND the 10 copied tracks to the same audio output (which would come from the hardware “X”).
Maybe not exactly what you needed, but it may help to better understand how to help yourself resolve your situation.