Sennheiser HD 650 Open Back Headphones Review

Sennheiser HD 650 Review

Headphones from the Sennheiser HD series enjoy a legendary reputation in terms of production technology and sound. So that it stays that way in the digital age, the Wedemarker have teamed up with a protagonist of the finest converter technology, the American manufacturer Apogee. We have taken a closer look at the Sennheiser HD 650 Groove Bundle components and tell you what to expect.


  • Extraordinary bass response
  • Warm, natural, detailed sound
  • Very comfortable
  • Great build quality


  • Bulky and heavy
  • Some coloration in the treble
  • Still expensive


High-quality converters determine the sound quality and the listening experience.
It is not only the quality of the electromechanical transducers that determines the sound, and thus the listening experience, the electronics in front of it are also important. It used to be relatively easy. First, you plugged the headphones into the connection provided on your home hi-fi amplifier, at which point the sound from the speakers fell silent, and you could enjoy the music under your ear cups.

Today, most music comes from the home computer, be it from the hard drive or via streaming from the Internet. In both cases, it is necessary to convert digital audio formats to analog signals, requiring adequate amplification to power headphones.

Stereophonic audio streams up to 192 kHz and 24-bit data width.

And this is where the problem begins: PCs and mobile devices nowadays have integrated D / A converters, but these are mostly cost-optimized circuits whose quality seldom comes close to high-quality converters. In addition, good headphones can only achieve their full potential if the amplifier provides sufficient power and headroom even at higher impedances. This is where the Apogee Groove comes into play: Equipped with four ESS Saber converters per channel, the converter can process stereophonic audio streams up to 192 kHz and 24-bit data width.

At the same time, the downstream output amplifier can also handle high-impedance headphones such as the Sennheiser HD 650 (impedance: 300 Ohm), which lets us play loud enough. With dimensions of 95 x 30 x 16 millimeters, the device is only slightly larger than a lighter and lies comfortably in hand thanks to the aluminum housing with elegantly rounded corners and edges. At the top, there are two rubber buttons for adjusting the volume. At the bottom, there is a 3.5 mm jack socket for headphones. Operating power and digital audio stream enters the device via a mini-USB socket on the front.

Practical: detachable connectors on the ear cups

Sennheiser delivers the Sennheiser HD 650 in an elegant, dark cardboard box. Foldable and hinged, it is not only used for transport but also as a storage place. For this purpose, there is a suitably shaped foam insert inside, which also offers space for the Apogee Groove converter and USB cable. Thanks to the detachable plug connector on the ear cups, the supply line can be easily exchanged in the event of a defect. It is also possible to purchase a longer alternative (3 meters, 6.3 mm jack plug for hi-fi amplifier) ​​instead of the short cable (1.4 meters, 3.5 mm jack plug) included in the Groove bundle. If the cable is under strong tension when jerked, it cannot tear because the connector will loosen beforehand.

Open design

The headphones are made of impact-resistant and break-proof plastic, whereby the dark-metallic coloring supports the appearance perfectly. The dynamic transducers are closed off from the outside by two transparent perforated diaphragms. The Sennheiser HD 650 is one of the open listeners despite its enclosing ear pads. They are lighter and more comfortable to wear than closed, “hot ears,” thanks to the air circulation around the transducers, which do not set in so quickly. The length adjustment of the headband works in a known way with notches. If the ear pads are worn out, they can be exchanged in a few simple steps.


Simple “plug and play” installation under OS X
Commissioning the Apogee Groove on Apple computers from OSX 10.8 is particularly easy. If I plug the converter into a USB port on my MacBook Pro, the playback of iTunes via the internal speakers is muted and is redirected accordingly. Three LEDs between the volume buttons indicate the digital level. To use as many bits as possible and thus the sound potential of the groove, I increase the level in iTunes until the third LED lights up green but not yet read. The listening volume is set in fine increments using the pushbuttons. The LEDs change to purple and show the current volume level for a moment. If the bottom LED lights up blue, the device is ready for operation but is not receiving any audio.

Drivers for Windows must be installed separately via download.
Windows 7 and higher users need a driver from The setup follows the usual Windows procedure and is done quickly. However, operation under Android / iOS is not planned, probably due to the power consumption. The converter indicates this heats up after a while, i.e., it produces power loss, which the batteries of mobile end devices are likely to use excessively.

Relaxed listening and a detailed sound image

And how does it sound? Noble! Assuming high-quality recordings, the Sennheiser HD 650 creates a beautiful spatial and detailed sound image from the signal from the Apogee Groove. Although the open design is usually said to be different, the HD 650 can go deep into the bass without the bass range appearing generally overrepresented and obscuring sound details. On the contrary, the bass drum, bass, and other low-frequency details always remain locatable and defined, which speaks for the good impulse fidelity of the Sennheiser converter. In addition, there are well-measured, non-intrusive mids and finely drawn highs.

It is not necessarily analytical but rather pleasantly balanced hi-fi sound that does not tire the hearing even over a long period. The HD 650 is also comfortable to wear: Weight and pressure perfectly complement relaxed listening. If both cushions surround the listener’s ears so that nothing presses, the headphones fit like a glove, and nothing stands in the way of long listening sessions. Most of these will take place in the home. Unfortunately, the Sennheiser HD 650 does not work in the studio, for example, for singing in vocal passages, due to its open design. Here, as well as live on the DJ set or FoH, closed models are mandatory, ensuring the necessary acoustic isolation against crosstalk from the playback into the recording microphone or against high ambient levels.

And how important it is to have adequate preamplification is shown when I try to bypass the Apogee Groove and plug the HD 650 directly into the headphone jack of my MacBook Pro. The quality of the sound drops noticeably. It sounds flatter and less loud because the computer’s analog output, which is intended for low-impedance listeners, does not have enough headroom to drive relatively high-impedance headphones such as the HD 650 adequately.


In the age of digital music consumption, Sennheiser and Apogee forge a useful alliance. The combination of Sennheiser HD 650 and Groove delivers a powerful bundle that meets high demands in terms of quality and sound quality. The Apogee Groove provides the template with high-quality D / A conversion plus amplification, while the Sennheiser HD 650 ensures the perfect sound finish with its wearing comfort and quality converters. A team that makes listening to music fun.


Sennheiser HD 650 Open Back Headphones Review
Sennheiser HD 650 Open Back Headphones Review


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