This Sennheiser has a very good sound. It is "richer" than Sony MDR-7506 (I also), but less comfortable. It provides more bass and is more balanced in frequencies. More dynamic than the Sony (which is already, itself, a very good headphones). It is in some ways more Hi-fi, but with great dynamics and responsiveness. The Sony MDR-7506, would be a helmet studio musician (many medium) and Sennheiser HD25 headphones plus a mix itself and to non-professionals, the acoustic comfort of the Sennheiser wins.