How many amps per circuit is the planned draw?
Regardless 10awg will work. Home Depot, Walmart, Menards no difference. All will meet NEMA specs.  

Yes, that looks good. 10/3 gauge is good. 

 

Make sure you think it through. One or two amps? They are between speakers. If you are going mono block, then two might be better for the amps. Run the other for your other components... to the side? 

Unfortunately, I originally only ran one line, then had to run another. Would have been cheaper to do it all at once.