Czar,
I have old Stax phones still that I use regularly and just added a set of Sennheiser Momentum phones, which deliver the expected Sennheiser sound out of a more portable and easy to drive package than some other Senns.
Sennheiser and Stax are two different beasts with two different sounds for sure, but I do enjoy each on their own terms in that each is VERY GOOD, but in different ways.
Headphones are interesting in that no two probably sound exactly the same, yet so many can be quite enjoyable. REinforces to me what I already believe in that there is no absolute sound. Just like there is no absolute wine, ice cream, car, woman, etc. But with headphones, there is a huge # of very good ones to choose from these days, geared towards different users.
Interesting stuff.
