We really wanted to like the MB2.5 as we were considering the line from a distributor we already have a relationship with. The price, size and look of them is all very attractive. We tried out a pair that had about 100 hours on them and proceeded to put on about another 500 hours. When we first received them, they were unbelievably boomy. The boominess did lessen over time, but even with about 600 hours on them, they were still far too boomy for us, even very free from room boundaries, so we gave up. We didn't try plugging the port, even though we knew it would help. Our thought was that if we were well away from room boundaries, fed them ample high-quality power, had 600+ hours break-in and they still didn't sound good, they weren't for us. Too bad. We hooked up a pair of ATC and were very happy again.
