Any 3.5mm headphone will be physically able to be plugged in to the mixamp, yes. As for being able to drive the headphones properly, the answer is probably (unless you have high impedance headphones or something).
Dolby 7.1 surround has nothing to do with the mixamp. The mixamp is a headphone amplifier that has 2 line in's that allow you to exchange the volume of one for the other. Surround sound has to do with the number of drivers in the headphones as to whether it is truly 7.1. I would personally recommend a decent set of stereo headphones, but then again I don't know what you're using this setup for.