AG08,

First of all, congrats on your purchase. I'm happy that the M3s please you. Now about your issue. I think you can solve it by adding a subwoofer. It would take the burden of producing low bass off your M3s and result in a cleaner, more effortless sound when you play them loud.

Becuase the M3s already blow your former speakers away as-is, you can continue to enjoy them alone until you've saved up the cash to buy that sub.