alphacore users break in question

Just upgraded to Alphacore MI2 spk cable. I demoed these before I purchased and they were phenomenol in my system. Is there a huge improvement after break in with these cables? After about 10 hrs the new cables sound horrible. The demo cables were a bi wire pair 15' long and mine are 4 pair 30' long. My dealer assured me that they would sound the same at 30'. I hope they will.

Thanks