When I got the HD 58X, I expected the sound quality to be comparable to my HD 598's given the price, but I was so wrong. The bass and clarity on the 58X is metric miles ahead of them. The 58X have effectively replaced my Stax L300 and TH-X00 PH as my daily driver. They're close enough to the mid-fi cans in sound that I don't bother with pulling out those two less comfortable cans.