Series Power Supplies?

[j4570]

I need 90 VDC to test an old battery radio.

Can I hook up a couple of triple power supplies (each is 5V/20V/20V and can be added together for 45V, then I need two of them) to get 90 VDC? Or is there some ground problem/issue I am not aware of?

I'll post over in videokarma too, since this is for an old radio.