Sennheiser HD 660 S vs HiFiMan Edition XS

The HiFiMan Edition XS are better audiophile headphones than the Sennheiser HD 660 S. The Sennheiser have a dip in the treble range that can make audio sound slightly veiled. By comparison, the HiFiMan have a much more neutral treble range and have more low bass, so kick drums and basslines have more thump and punch than the Sennheiser. Despite both headphones being over-ear open-backs, the HiFiMan have a far superior passive soundstage, producing a much more speaker-like sound than the Sennheiser. That said, the Sennheiser are slightly cheaper.