Sennheiser HD 650 vs V-MODA Crossfade M-100

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.

The M-100's sound signature can work really well with a wide range of music. Bass reproduction has good power and punch. The mids are also full and slightly forward over the other frequencies. This results in extra emphasis on the vocals and on mid-range sounds like guitars and keyboards. The highs are not peaky, which reduces their harshness, sounding smooth instead.

These headphones come with a SpeakEasy Mic cable and a Share Play cable. This gives you an option as to which cable you want to use at a given time. This also means that you will have a spare cable should you damage the other.

These have a solid, high quality feel to them, and you can tell that they will last you a long time. The ear cups are made of high quality plastic, while the headphones' yokes and headband are made of metal. The headband has a generous give yet does not feel flimsy at all. You can even twist it quite a bit yet it still won't feel like it will break.

The yokes can be collapsed and folded up into the headband. This reduces the overall size of the headphones, making them much easier to carry around.

You can detach the cable by simply pulling out the 3.5mm connector from the port on the headphones. The connector attaches with a satisfying click so it is less likely to get disconnected when in use.

The SpeakEasy cable has an in-line microphone with great noise cancelling. The cable also comes with an in-line 1 button remote which allows users to answer or end calls, as well as pause and play music tracks.

The SharePlay Cable features a 3.5mm pass-through port where a person can connect their own headphones. This means that you and another person can enjoy music from the same source.

Included is a clam-shell style case made of durable plastic so it should protect your headphones from scratches and minor impacts. Do note that you will have to detach the cable to make it fit inside the case.