The Sennheiser HD580 is one of the best-bang-for-the buck purchase in the world of headphones. Used units go in the $100+ range, and the sound is virtually the same with the higher priced HD600. The HD600 headphone has gained a renowned status as the reference headphone for amplifier designer Ray Samuels and Ti Kan from AMB Labs. That means, for $100+, you can get a headphone that sounds very much alike to the reference headphone Ray Samuels and Ti Kan uses.
What was Sennheiser thinking when they use the same driver on the HD580 and the higher priced HD600? The HD600 does use a more expensive, more rigid material for their housing, and that may affect the sound somewhat. But most of the time, people cannot tell the difference between the HD580 and the HD600. Provided that they uses the same version of drivers. (Please read the article on the driver versions here: https://headfonia.com/blog/sennheiser-hd650-600-and-580-updated-drivers/)
A lot of people actually prefer the matte finishing of the HD580 to the fake-marble finish of the HD600. And with a grill change, the HD580 really looks sharp! We don’t know for sure if the grill change alters the sound of the HD580, but the HD650 cable definitely makes the sound smoother and more refined. A brief A/B-ing between the HD600 and the HD580 tells us that the sound is identical. This is with the HD580 using a HD600 grill.