Neighbor Complaining...

I lived in a condo for 10 months and never met the neighbor next to me until 20 minutes after I hooked up my subwoofer.....

Buy a house or take up another hobby.

If you don't have a sound level meter, buy one. (The Radio Shack models can be had for about $50.)

That can form the basis for really finding out how loud you listen and also what level bothers the neighbor. If you're a 100 dB kind of guy, you've got your work cut out for you.

However, the above suggestion about inviting the neighbor over and offering to work with him on both the volume and hours issue is a great idea. There is a fair (though certainly not absolute) chance he might try to meet you halfway.

Get a house, headphones or a louisville slugger.

Moving the speakers to the other wall will help however you can greatly reduce the sound transmission through the common wall by screwing 2"x1" timber battens @ 18" centres to the common wall with 1/4" rubber pads between the battens and the wall at the fixing points. Fix 2" fibreglass insulation floor to ceiling between the timber battens and screw/glue 2 sheets of 5/8" (16mm) dense plasterboard one on top of each other, to the timber battens leaving 1/4"-1/2" gaps at both floor and ceiling which you then seal with silicone sealant.