I decided two month ago to purchase a Beyerdinamics 990 pro.

The key features of this headphone are a solid design with high grade materials, an open design for the cans that provide a more realistic scene and soundstage.
There is also the fact that many replacement accessory are availiable aftermarket. Beyerdinamic provides the headband and two types of pads ( velour / pleather) as replacement parts.

Sumarising the dt 990 pro:

the + :
● good soundstage (open design)
● confortable for long listening session
● good resolution, balanced and good placement of instru/effects
● materials of good quality : metal/velour/plastic

the – :

● no isolation so can be used only in a vert calm environment (max 40 db of back noise)
● dont works with portable devices like ipod except some smartphones (galaxy note, s3) Idealy need an amplifier
● some person may wants more presence in low frequencies but everything is here (depends on yout taste)

The DT990 is a very well-made product, the parts are made from velour, metal and plastic of good quality. All the parts are replacables (headband, pads…)

It is actually the most open headphone that I’ve tested. For example the isolation of a DT880 or a Superlux HD330 is a little bit superior (semi-open design). The good aspect of the sound with this headphone is that it appears really balanced to me. With a slight emphasis of the bass/sub region but not some kind of loudness or boomy accentuation. It is something very subtle and detailed. This equilibrium in the bandwitch permits to have a  very critical listening session. Some headphones more “fun” for example like the Superlux HD330 give a more engaging restitution more suitable for hifi. With the DT990 everything is more flat. The quality of the tones in the high freq is very good I think and it doesnt lack details.

So dont expect an accentuated midrange or a zoom in the highs with this one. With a decent source/amp the experience can be very pleasant. Ideally it requires a decent amp to give the best performance.

Top of the pro line with the DT 880 there is now the T1 and T90 with the technical improvment of the Tesla driver and an open/semi open design. I definitively want to give a try to this 2 headphones and listen how they compare to the DT990.