I picked up my HE4XXs this morning and I am seriously impressed. This is my first pair of planar magnetics and the only headphones I have on hand to compare them to are my HD650s. They easily hold up to my HD650s sound quality wise. Absolutely worth the money. Bass response is a bit more punchy than the Sennheisers with a bit more dropoff on the low end. Highs are definitely more resolved on these. A bit more sparkle in the trebles as well. Mids are slightly recessed as compared to the HD650. The soundstage on the HE4XX is a bit smaller/more compact than the Sennheisers. The Sennheiser's soundstage is wider and a bit more airy while the HE4XX is more narrow and impactful. Overall I am impressed with the sound quality and resolution at this price point.