Package Includes: (4) Beyerdynamic DT-770-PRO-32 Ohm Studio Headphones for Mobile Use(1) Mackie HM-400 Pro Rackmount 4-Channel Headphone Amplifier w/12 Headphone outputsAuthorized Beyerdynamic Dealer! Features of DT-770-PRO-32: Beyerdynamic DT 770 Pro 32 Ohm Dynamic Studio Headphones 32 Ohms drivers for mobile applications Closed diffuse-field studio headphone Bass reflex technology for improved bass response Comfortable fit due to rugged adjustable soft padded headband construction Robust easy serviceable construction as all parts are replaceable Softskin circumaural ear pads Single sided 1.6 m (5.2 ft.) straight cable Including drawstring bag Gold plated jack plug (3.5 mm) and adapter (6.35 mm) Details: Transducer type . . . . . . . . . . . . . . . . . . . Dynamic Operating principle . . . . . . . . . . . . . . . . Closed Nominal frequency response . . . . . . . . . 5 - 35 000 Hz Nominal impedance. . . . . . . . . . . . . . . . 32 O Nominal SPL . . . . . . . . . . . . . . . . . . . . . 96 dB SPL Nominal T.H.D . . . . . . . . . . . . . . . . . . . . < 0.2% Power handling capacity . . . . . . . . . . . . 100 mW Sound coupling to ear . . . . . . . . . . . . . . Circumaural Ambient noise isolation 32O version . . . . . . . . . . . . . . . . . . . . . approx. 20 dBA Nominal headband pressure . . . . . . . . . approx. 3.5 N Weight (without cable) . . . . . . . . . . . . . 270 g Length and type of cable 32 O version . . . . . . . . . . . . . . . . . . . . . 1.6 m / straight cable Connection . . . . . . . . . . . . . . . . . . . . . . Gold plated stereo jack plug (3.5 mm) and 1/4 adapter (6.35 mm) Click Here To View The User Manual (Link Opens In A New Window)Advantages of purchasing from an authorized seller: Best prices - We sell all Beyerdynamic Products at the lowest price as possible. Full Factory Warranty Detailed information of all products Lifetime Customer Service by Beyerdynamic Product Experts Guaranteed legitimate and authentic merchandise Please note: If you purchase Beyerdynamic from an un-authorized seller then you are taking a big risk. You will not have any manufacturers warranty and there is no guarantee that the item is authentic brand new or even working.Authorized MackieDealer Description of HM-400: The 19” rackmount HM-400 4-ChannelHeadphone Amplifier offers an incredible amount of versatility andexcellent sound quality in a single rack space. Perfect for professionalapplications including studios Houses of Worship practice spaces andmore. The HM-400 features a main input with level control plus stereoouts aux inputs and EQ per channel with 12 total headphone outputs. Features: Mackie HM-400