Hi Jeff;

I'm very surprised to hear about the problems with your M60 -- very unusual! There shouldn't be any problem with the inserts nor with cabinet resonance. I think the best idea is for us to send you a new pair of M60s right away and to have yours returned to us after the holiday rush, so we can investigate the issues here at the factory. Could you please email me so I'm sure I have the right person? Amie