Custom Made for Sennheiser HD Series Wired Headphones. This wireless music adapter works as a wireless audio streaming converter for the Momentum series headphones, Sennheiser HD598 / HD598Cs / HD598SE / HD595 / HD599 / HD559 / HD569 / HD579 / HD518 / HD558 Headphone replacement cable cord connector and converter. | Excellent Sound Quality. This Bluetooth audio receiver has a dedicated Texas Instrument headphone amplifier chipset built-in which makes it more dynamic and rich in details. The output is much more powerful, it can drive the over ear headphones with larger impedance, so this is a wireless receiver plus a headphone amplifier and it is perfect match for Sennheiser HD series headphones. | Optional Bass Boost Feature. Airfrex Bluetooth receiver has preset EQ function which allows users to turn on or turn off the bass enhancement feature if needed, this feature can compensate the bass performance for their headphones or speakers, users just need a simple double click to switch this function. | Latest CSR Bluetooth 4.1 Chipset. This wireless stereo adapter applies the most advanced CSR Bluetooth chip which ensures this is lossless in audio transmission which is a huge difference from those low quality Bluetooth adapters. You need a high quality headphone adapter for a good Sennheiser headphone. | Built-in Microphone for Phone Call. Our music adapter also has built-in Microphone which allow the users to pick up or end a phone call by a simple press on the button, so they won’t miss any phone call even during music listening.