I think it can be in line with any other amp to speaker situation as it doesn’t ‘draw’ on the amps impedance….so you could be running a 4 ohm amp into 4 ohm speaker(s) but still hook this up to the system without affecting the ohm load to the amp.
I have one of these, they are very good and at last, your own dedicated bass monitor! The volume isn't anywhere near as loud as your main speaker but at ear height, especially in the acoustic setting, it gives a great ‘ear’ experience.