We listened to the HD 598 with an Onkyo TX-SR805 receiver, a Schiit Audio Asgard headphone amplifier, and an Apple iPod Classic. The headphone's sound is superclean and has a wide-open soundstage. Tonal balance is a little brighter and emits more treble detail than we've heard from previous generations of full-size Sennheisers. Even so, it's a very easy headphone to listen to over long listening sessions.
Deep bass on the Sennheisers has tremendous impact and power, so the big drums on Grizzly Bear's "Vecktimest" CD sounded terrific and the soundstage is remarkably spacious. The headphone's open quality works especially well with movies like "Cairo Time." When Juliette Grant (Patricia Clarkson) first arrives in Cairo, she's picked up at the airport by her husband's friend Tareq (Alexander Siddig). As they drive away, the sounds of the busy city streets surrounded us, and the dialog sounded exceptionally natural.
The Sennheiser HD 598 sounds fine with Crosby, Stills, Nash & Young's live album, "4 Way Street." The liveness and clarity of the recording is well preserved by the headphones, but while the HD 598 can play loud with iPods, the drive may still fall a bit short for some listeners.
Still, we wouldn't recommend the HD 598 to buyers who only intend to use the headphone with an iPod or other portable music players. Bowers & Wilkins' similarly priced but smaller on-ear P5 headphone is more dynamic and transparent and has better bass definition used with an iPod, but we much preferred the HD 598's sound over the P5's at home plugged into a receiver or headphone amplifier.