yeah, probably, but its not so much whether its balanced or unbalanced thats important to know, more what level the signal is.
I would imagine the xlr out is a DI out, either very low level or possibly line level. both these will work fine going into the xlr in on your interface, which I assume is a mic pre amp, however if it is a line level signal it will be very loud and may overload the pre amp.
most DI outs are instrument level unless specifially stated. if its not a DI but a speaker out (which is unlikely, but possible) you should definately NOT plug it into your interface, speaker level is a much higher voltage signal that could cause damage.
so it will more-than-likely work, but its worth a quick check of the amps manual to find out if the xlr out is a DI (it'll probably be labelled next to the socket anyway!)