Sennheiser HD 650 vs Plantronics BackBeat Pro 2

The sound signature is near neutral but with a little emphasis on the lower frequencies. The bass is slightly forward with good punch and tightness. Explosions will have good rumble, without overpowering the other frequencies.
The mids are warm and clear, adding extra body to the sound. Game dialogue will be easy to hear.
Highs have good clarity, but are not forward in any way, so harshness is minimized.

The H650 is popular for its near neutral sound, which makes it quite versatile. The headphones can give a great casual listening, gaming, and movie watching experience yet are accurate enough for pro audio mixing. They are also lightweight and comfortable so you won't have any issues wearing them for hours.

Clamping force is not too tight. The ear pads and headband feature memory foam which are covered by velour material. The pads feel really soft on the head and allow airflow for minimized heat build-up/sweat.
The headband also features similar cushioning materials and minimizes pressure spots on the head.

The open ear cup design allows the sound to blend with your surroundings, giving it a natural width. It will also be easier to identify the direction of sounds, which can really help immersion.

The HD-650s do not feel heavy at all. They are usable for long music listening, movie or gaming sessions without feeling pain or strain on their head and neck.

While the cable connectors are proprietary, they can easily be removed from the ear cups with a firm pull. The popularity of these headphones means that there are a lot of aftermarket cables that can be bought.

With the BackBeat Pro 2, you get powerful yet clear sound that is comparable to higher end models but at a noticeably more affordable price. Wireless range and stability is quite good and the noise cancelling, while not the best, can reduce a good amount of external noise.

While the active noise canceling is not the best, it is able to reduce a good amount of noise from your surroundings. Loud engine sounds or high pitched noise may still mix in with your music though.

The BackBeat Pro 2’s mids and treble are not forward, yet sound clear and neutral. You may hear a bit of sharpness in the higher frequencies, but overall you’ll get a pleasant listening experience with great details from your music.

The low-end is quite emphasized, so you’ll get a lot of thump from bass hits. Bass lovers will likely find these headphones to be up their alley.

You won’t need to press a button on the headphones or on your source device to pause the music when you need to remove the BackBeat Pro 2. There are sensors inside the headphones that detect this motion, so the music is automatically paused, and then resumed when you put the headphones back on.

Listen to the environment via a microphone without taking off the headphones.

These headphones have Bluetooth connectivity for wireless convenience, but you can also switch to 3.5mm wired mode if the battery runs out and you cannot charge right away.

You’ll be able to hear audio even if you are around 100 feet away from your source device, provided there is a clear line of sight. Signal quality is also pretty good with minimal music cuts and drops.

These headphones can last up to 24 hours of playback from a full charge, and this with moderate volumes in wireless mode with noise cancelling activated. This is very good battery life, considering other wireless headphones at the price range only have around half the battery life on average.