Two 128's powered by usb hub-is it safe to use ext 5v power supply?

Im hage two monome 128’s plugged into a powered usb hub (belkin)connected to a computer.
I would like to add other usb de devices to this hub, but im running out of power.
Could i use one of the ext. 5v supplies (one i got for the meadowphysics module)? The idea is plug the ext 5v to one of the monomes and the other usb end of hte 5v supply into the usb hub.
Would that lower the power drain from the usb hub, so i can plug more usb devices.
Id like to make sure before i mess up something.

ext5v will remove any 5v demand from the host, so yes, your idea will work. though a usb hub (a good one?) should be able to source a lot of current. i have a nice on from anker that works well.

Thanks for the reply Tehn. I ended up getting another usb hub. The Belkin ones seem to provide enough power.