Koss ESP 950 were state of the art in yesteryear. Unfortunately, they can't begin to compete with Stax models available in 2016. My choices would be the SR 009, or Omega Mk1. It's always a good idea to pair them with a Stax driver unit. There are many headphone amplifiers that can outperform even Stax amps, like Blue Hawaii or Woo Audi, but both are very expensive. Other brands to consider would be Audeze, Hifiman or Oppo.
Which Stax headphones- best bang for the buck
I would like to replace my Koss ESP 950 headphones with Stax headphones. Naturally, I would like to make a step up. Which Stax headphones (and amplifier) offer the best sound for the money and why? Thanks in advance.