Beyerdynamic were there right at the start of audio electronics, in the 1920's. Their products helped shape our expectations of what headphones ARE, in fact they developed the very first dynamic headphones (DT48) somewhere in the 1930's.
Some of their microphones have become classics too, like the M88, still current, around since 1963.
The communication headsets (DT108/109), that look similar to the headphones we are reviewing here, have been around for close to half a century and have become the broadcasting standard around the world.
I also own the DT990, a pricey top of the line consumer open back model, as well as the DT990Pro, an open back professional model. The latter is my absolute favourite for comfort and sound quality. The model we are talking about here, the DT150, is the professional closed back type. All the little parts are replaceable, and the look is similar to the grey DT100 series that have been around for a very long time.
Soundwise these hold their own with the top of the line domestic models, with the advantage of servicable parts and great durability. Compared to the earlier models these have more robust low end.
I use these in a recording set-up where I need reliability and a soundquality that inspires people to give of their best and make great music. What surprised me was that as well as being excellent sound isolators they sounded so good! To my ears these modern DT150's sound much better than the DT770Pro, let alone the DT770M, the latter may isolate slightly more, but somehow sounded way too boxey and dull for me.
I can heartily recommend the DT150's in a professional setting, and if you need the extra isolation at home, they are close to some of the best headphones you will ever hear, surprising for something built like the industry workhorse that they are :)