Headfi: Master & Dynamic MH40 review October 09, 2014 in headphones Headfi forum member, grizzlybeast, just posted a review of the Master & Dynamic MH40, an awesome headphone whose prototype I briefly evaluated. The short is that it sounds good, but isolates less well. While these headphones isolate fairly well, I will make a gripe about leakage. As easily as these seal around my ears I would expect them to leak a little less. They leak a little more than average without striking them out from being portable. If I was on a loud bus I would be able to enjoy my music easily but the person next to me would be hearing much of my music if it was loud. I wouldn’t say you would be obnoxious though. This is not deal breaking leakage but also not ideal. Be sure to check out grizzlybeast's review.Next week I will follow up with by finally publishing my review of them at Headfonia.