There is no reason not to try this, but gain matching will be your biggest challenge. If one amp has, say, 27dB of gain and the other has more, or less, you can either have a technician adjust one of the amps (if the design allows it) so that the gain of both is identical, or try inserting an extra potentiometer (which, with extra cabling, is sure to degrade the sound), or give up on that combination of amplifiers.
