I`ve recently had the port on my ABM410 closed off. I spoke to Ashdown about what I was after, as the cab seemed too "wampy" and backing off of the bass, although getting there, wasn`t getting as near as I wanted. They suggested closing off the port so last week I stuck a towel in the (front) port. Instantly the sound I want was there, tight and focused, it really made that much difference. Previously, using my Para Driver as my main eq I still had to use the eq on the amp to back off the lows and up the high mids, now I have the eq on it bypassed using only the Para Driver.