I've never actually tried any hifi man headphones so take this with as many grains of salt as required but I've heard that the egg shaped models like Edition XS or the Arya are more similar than they are different. Also that the build quality is spotty so out of the two could go for XS as it's priced better and eq to taste. Plus the XS has better extended bass and more treble than the HD600s which seems like a good fit to your needs, but I'd recommend buying from somewhere with a good return policy to be safe.