Sennheiser HD 800 S Dynamic Open-Back Stereo Headphone Kit with Grace Design M900 Amplifier

An update on the well-regarded HD 800, the HD 800 S by Sennheiser comprises a pair of open-back headphones designed for use in studio situations, particularly when referencing between monitors and cans. Its 56mm transducer is housed in stainless steel, while its headband and mounting utilize industrial, aerospace-grade materials to emphasize durability at a relatively light weight of 11.6 oz. Sennheiser's proprietary sound absorber technology preserves the integrity of the highest of high ends by eliminating the "masking effect," a phenomenon in which the ear struggles to hear particularly bright signals when lower-frequency material occurs simultaneously at a louder volume. In reducing this masking effect, every nuance of the frequency spectrum is represented and made audible.

The design of its earcups directs sound to the ear at a subtle angle, thereby aiding in a realistic—and realistically stereo—monitoring experience. Additionally, there are two different possibilities for audio connection: a stereo 1/4" connector, and a 4.4mm balanced cable for connecting to balanced outputs, such as a headphone amplifier.

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'.)