Question about MIDI wiring

[Katch]

Wasn't really sure where to ask this question and Midibox was the only community that I could think of that would have the knowledge to help.  I have a couple of old Allen and Heath Xone 1D controllers.  They have a built in USB MIDI interface that they have abandoned support for.  Short version, they no longer work above Windows 7 or OS X Mountain Lion, rendering them pretty useless today.

As a workaround, you can power them over USB and then feed MIDI out via a cheap Chinese 1x1 USB MIDI cable.  Now this is less than ideal, as now I need 4 USB sockets as well as trailing 4 MIDI cables from the back of the units.

So I was wondering if I could do a bit of a ghetto mod and fit the USB MIDI interfaces internally?  Basically open them up, solder the MIDI IN and OUT directly to the IN and OUT sockets from the inside of the chassis. Disconnect the USB data +/- from the built in MIDI interface and then connect the 5v/Gnd/D+/D- from the new interface to the panel mounted USB B socket.

In theory, this should allow me to plug a single USB A to B cable into each unit which will power the controller and the new MIDI interface. The interface is hardwired to the sockets, so I should get MIDI signals IN and OUT over the new interface.

My only unanswered question is, will the MIDI IN OUT THRU on the back of the unit still work as expected when hard wired in this way?

Also, I know I will need to be careful about current draw when wiring up the 1D and the new interface together on the same 5v source. I'll check current draw of both parts before committing to this idea.

Edited June 6, 2019 by Katch

[latigid on]

Probably doable, but I think it would be easier and safer to interface outside of the box. Do you know how much physical space is inside? Photo?

I don't see the benefit of plugging in the MIDI cable versus soldering it. Have you considered using a MIDI hub/4x4 router box? You could also use a USB router for the power connections.