Unbalanced cable is easy to find and relatively inexpensive.

Generally unbalanced cable in a balanced connector is fine.

Balanced cable in an unbalanced connector comes with stipulation. Depends on the wiring and components on the other end. That's why my suggestion would be to pay the 0.66% tax (less than 1%) vs. the price of your keyboard and invest in a cable that's right for the job. Professional musical equipment is no small investment and should not be burdened with sub-par accessories (interconnect/cables - amplification - etc). Particularly when $20 (or thereabouts) is what we're talking about here saving.

I generally purchase different colored insulation for cables that are a different type. Balanced are black. Unbalanced I have as blue currently. Makes it easy to sort out. I keep the cable for the keyboard in its own bag with my other keyboard accessories.

Trying to address some of the other reasons one may have for wanting to not throw in another cable type in the mix (losing among a sea of balanced cables).

Unbalanced cable is easy to find and relatively inexpensive.

Generally unbalanced cable in a balanced connector is fine.

Balanced cable in an unbalanced connector comes with stipulation. Depends on the wiring and components on the other end. That's why my suggestion would be to pay the 0.66% tax (less than 1%) vs. the price of your keyboard and invest in a cable that's right for the job. Professional musical equipment is no small investment and should not be burdened with sub-par accessories (interconnect/cables - amplification - etc). Particularly when $20 (or thereabouts) is what we're talking about here saving.

I generally purchase different colored insulation for cables that are a different type. Balanced are black. Unbalanced I have as blue currently. Makes it easy to sort out. I keep the cable for the keyboard in its own bag with my other keyboard accessories.

Trying to address some of the other reasons one may have for wanting to not throw in another cable type in the mix (losing among a sea of balanced cables).

Thanks,
I get all of that.

I currently use all Mogami Cables.
The reason I asked is for instance, my RME UFX Plus uses both Balanced TSR and Unbalanced TS on the same ports, both formats will work.

I am simply trying to figure out if the Montage will accept both formats, this way I do not have to get another cable.

But looks like I need to.

Thank you as always.

The Montage balanced Main L&R outputs - like your balanced RME ports - also accept unbalanced cabled (both TSR and TS). That's generally the rule.

It's not that it can't work the other way around - just that there's more to it to tease out if it's going to work at all - or work degraded - or work just fine.