Sennheiser HD 650 vs Razer Man O' War

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.

Razer's Synapse application gives users a lot of features to tweak and control. Some features that can be controlled via this software includes EQ, 7.1 surround sound, RGB lighting settings and many more.

Each ear cup features the Razer logo and has RGB lighting underneath. Users can customize the light color and glow patterns of the logo, and sync them with other Razer peripherals if desired.

The mic can be pushed in or pulled out of the headset as needed. The mic is also flexible, allowing a user to bend the mic to the desired position.

The ear pads feature thick foam cushioning. Combined with the use of supple faux leather on the ear pads' surface, the headset is great to wear for long gaming sessions, as it is less likely to cause pain on the ears/side of the head.

A lot of plastic is used in the construction of this headset, including the head band and the headset's yoke. This makes the headset quite lightweight despite being large, so this is not too tiring to wear, even for long gaming sessions.

The highs are what make this headset sound good. They are slightly boosted yet are not harsh, which results in a lot of detail.

Bass reproduction is okay. While there is not a lot of bass rumble and punch, the bass is present enough to prevent the sound from being too lean.

The mids are slightly recessed though, so some movie or in-game dialogue can be a little more difficult to hear, especially when there are a lot of explosions and similar sound effects present.

Audio from the mic is clear without too much distortion. Also, it doesn't sound tinny like most integrated mics do, so teammates will clearly hear your voice. The mic also has great noise cancelling properties, so button/keyboard presses or mouse clicks will be near-inaudible.

The sound can be substantially changed via EQ adjustments so you should be able to easily dial-in the sound that you want to get.