I am looking for the best way to hook up my AX120a sub to my amp for best quality. It seems the only way I can use it is use the line level jacks even though I have the High level inputs and outputs. Any help would be appreciated. Can send pictures of sub if this would help.
Thanks in advance ..Mel.

Mel, you haven't fully described what sort of provisions for bass management your amp or receiver and your sub have. In general, the best procedure is to use coaxial cable from the sub out on the receiver(setting the receiver to sub yes or on, of course)which will then cross over to the sub below about 80-90hz. All the speakers should be set "small" on the receiver and the crossover control on the sub should be bypassed if it has that setting, or otherwise turned all the way up to get it out of the way of the receiver crossover.