Sennheiser HD 599 vs Sennheiser HD 6XX

The Sennheiser HD 599 and the Sennheiser HD 6XX are fairly evenly-matched headphones, and you may prefer either. The 599 are much more comfortable and have a better passive soundstage performance, but their sound may be a bit muddy to some. On the other hand, the 6XX have a more stable fit, a better build quality, and a more accurate mid-range response, but their treble response isn't as neutral, so sibilant sounds are a bit dull. That said, there isn't a huge difference between the two sound profiles, and either pair is a great option if you're looking for headphones for neutral sound.