The HD 650 from Sennheiser are reference-class stereo headphones designed to deliver a true audiophile experience with an open, natural sound. Specially developed acoustic silk was used to provide uniform attenuation over the entire area of each ear-cup. The lightweight aluminum voice coils ensure a remarkable transient response, while the full-range drivers offer a frequency response of 10 Hz to 39.5 kHz. Great care was taken to ensure the headphones are comfortable with their elliptical design, which naturally adapts to the shape of the ear.





The HD 650 utilizes a 9.8' detachable cable made from a highly conductive OFC copper with low handling noise and low structure-borne sound sensitivity. The headphones can be used with high-output mobile devices and excel with high-quality stationary hi-fi components such as SACD, DVD-A, and CD players. The HD 650 ships with the detachable cable and a 1/4" to 3.5mm adapter.The Grace Design m900 is a compact, portable headphone amplifier, DAC, and preamp, well suited for audio professionals, music enthusiasts, or anyone looking for transparent playback from USB, S/PDIF, or TOSLINK sources. For small DAW setups, the m900 provides the same analog and DAC quality as Grace Design's large monitor controllers, but in a rugged, portable, and surprisingly affordable unit.





The heart of the Grace Design m900 features the latest generation AKM 4490 chip, which includes 32-bit processing and support for sample rates up to 384 kHz or DSD256. The USB interface operates in asynchronous mode allowing the m900 to be the clock master, which makes the system immune to USB bus jitter. S/PDIF and TOSLINK inputs enhance any DAW interface with true reference-quality D/A conversion, headphone monitoring, and stereo speaker control.





The intelligent power supply design allows for two power operation modes, Low and High. Low power mode is derived from USB connection 1, which provides bus power along with data, allowing simple operation from a single connection to a computer. High power mode is available by connecting the included 2A USB DC power supply to USB connector 2, which provides additional power for high-impedance headphones.





The Grace Design m900 utilizes trans-impedance amplifier topology coupled to a zero-ohm output impedance driver for headphone performance that is spacious and transparent with a tight, enveloping low end, while the latest generation cross-feed circuit rounds out the design by emulating an acoustic listening environment in the headphones. The Grace Design m900 ships with a 2A USB power supply and two USB Type-B mini-cables (6' and 10'.)