Lets review new monitor headphones Sennheiser HD 598. Manufacturer does not tell information about diameter of their drivers, but, judging by their view, it is 40 mm, they are driven with neodymium magnets and can reproduce sounds with 12 – 38500 Hz frequencies, thier impedance is 50 Ohms; manufacturer does not tell information about their sensitivity and signal to noise ratio. Package contains : Sennheiser HD 598 headphones themselves, TRS 6.3 mm jack – 3.5 mm mini-jack adapter and user’s guide. Overall, they are too overpriced ( 250 USD at the end of Autumn 2015 ) : in the technical details ( which not all are disclosed ) they are not better and in some respects even weaker, than top-level monitor headphones of Sony and Philips and cost much more, than they are; and for less than half of this sum professional studio monitor headphones can be bought, which are far superior in sound quality respect, than this handcraft. So, this is a classical example of marketing money pumping from customers with use of loud claims and names, which mean not much in technical respect; so, these headphones are not recommended for purchasing, it is better to buy top-level monitor headphones of other manufacturers with known technical details or professional studio headphones for much smaller price.