Combine with 10% ZipPay cashback deal to take this to $257.80
plus a further 4-5% cashback from the usual places, otherwise check out the AU-stock deal from Sennheiser with cashbacks. Sennheiser AU cashback has expired.
Neutral (flat, not Harman) open back with better bass extension, treble extension and soundstage than the 600 series, and the best clarity yet from the 500 series (but not 600 series level). There's some minor treble spikes (to promote soundstage) that some can perceive as higher still due to how the drivers are angled.
These would be great open backs for gaming, pretty much any music genre (including EDM-based tracks, which normally lose a bit with open backs), but doesn't have quite as natural a presentation or timbre as the 600 series (particularly the HD 600 and the 650/6XX).