Design and features:The headphones work with or without the noise canceling feature being turned on. You can use the noise-canceling feature without listening to music. These headphones can be used wirelessly with Bluetooth devices or can be cord connected. When cord connected they have medium-high sensitivity regardless of whether the noise canceling feature is turned on or off, so they can provide satisfying volume levels when used with home audio equipment and even lower-powered portable audio devices. They can also be connected to a computer via a USB cable to play audio files stored on the computer. The PXC 550-II has built-in microphones and integrated touch sensitive volume and music player function Bluetooth and USB computer controls, call connect/disconnect Bluetooth controls, and an ambient sound monitoring control. Additional features include two noise cancellation levels (one of which is adjustable), an auto pause feature that pauses or resumes audio playback when the headphones are removed from or placed on the head respectively, and support for Amazon Alexa, Google Assistant, Apple Siri, and other digital voice assistants when used with Bluetooth connected devices that have those features. This model has earcups that fold and swivel to flat for ease of carrying and storage, and comes with a detachable 55-inch long standard audio cable, a USB charging/data cable, a mini-plug-to-airplane-jack adapter, and a carrying case. The free Sennheiser Smart Control app download for Apple and Android mobile devices can be used to make general frequency adjustments, add reverb, adjust the spatial characteristics of the sound, enable the headphone's automatic pause feature, and to update the headphone's firmware.
Sound quality: In Bluetooth noise cancelling mode we found the PXC 550-II delivers Excellent active noise reduction and Excellent overall sound quality - while no headphone is perfect, the shortcomings of this model are minor. With the Sennheiser Smart Control app set at Neutral Acoustical setting (as received state of the headphone) the overall sound can be summarized as clear and crisp. The bass (as in bass drums, bass guitars, stand-up bass, etc.) has good impact and goes deep, but is a touch prominent and boomy. The midrange (voices, guitars, horns, etc.) is clear but a touch thin and etched (a bit more sharply outlined then it should be). The treble (cymbals, the upper range of violins, etc.) is extended and detailed, but somewhat prominent and a bit metallic. It does a good job of recovering room ambience (the sense of the acoustic space in which the audio program that's being listened to was recorded). The sound also has a good sense of liveliness and is open--sound-wise it seems like you don't have anything plugging up your ears. This model provides Excellent noise reduction across the entire frequency range with the low frequencies reduced the most. Orientation changes the noise reduction characteristic - when the noise is not coming from directly in front more mid-frequency noise can be heard. When the noise cancelling feature is engaged a very faint rushing noise can be heard when there is no audio program to drown it out. The Sennheiser Smart Control app acoustical settings had a noticeable effect on the sound. This model is susceptible to hiss when cord connected and used with some AC powered equipment.
Comfort: We found that these headphones produce a sense of medium pressure around the ears. As typical of on-ear models the ear pads might feel hot and/or sticky after prolonged use. Incidental contact with the touch control pad on the right earcup can cause unintentional volume level changes, playing, pausing, track skipping, or ambient sound monitoring. Users with larger heads might find that the headband presses uncomfortably on the top of the head. Users with larger ears might find that the over-the-ear fit of the ear pads feel cramped, or that the ear pads sit on, rather than around their ears. Some users may find that when they lean far forward the headphones feel unstable and shift forward, but not to the point of falling off. When wearing this model while walking the vibrations from each foot step may be faintly heard through the headphones. When shifting the head around the sound of the earpads rubbing on the head may be heard when their is no audio playing, but is less noticeable when an audio program is playing. When the audio cable is connected the sound of the cable rubbing on clothing may be faintly heard through the headphones.
