Beyerdynamic DT 990

The DT 990 belongs to Beyerdynamic's family of open-back dynamic headphones. Its earcups allow air to circulate behind the transducers, which does away with the confined feel typical of closed-back models: the sound image opens out and gains in depth, with a sense of space closer to listening on speakers than to listening in an enclosed environment.

The claimed signature is round and balanced, underpinned by a full, extended bass. This type of rendering favours expansive music, orchestral recordings as well as modern productions rich in low-end content, and is more forgiving over long listening sessions than an analytical rendering. The trade-off of the open design is well known and accepted: the headphones let in ambient noise and radiate sound outwards, which confines them to home use.

Beyerdynamic offers the DT 990 in three impedances, which change how it should be driven:

• 32 ohms, the least demanding version in terms of voltage, suited to low-power headphone outputs;
• 250 ohms, the common compromise for a dedicated headphone amplifier;
• 600 ohms, the most demanding variant, which requires a source capable of delivering sufficient voltage.

Comfort is the model's second selling point: a headband exerting reduced pressure on the head, generous earpads and contained weight. These choices are aimed at long sessions, where clamping force and weight eventually make themselves felt. The DT 990 is therefore intended for the sedentary listener, seated in front of their system or computer, who prioritises airiness and comfort over isolation and portability.

When buying used, a few points deserve inspection. Velour earpads compress, become shiny and get dirty over the years: their condition directly affects comfort and tonal balance, a crushed earpad bringing the ear closer to the transducer. Also check the foam on the top headband, often the first element to deteriorate, as well as the elasticity of the headband, since headphones that have become too loose no longer stay properly in place. Finally, listen to both channels separately to spot any imbalance or a clogged open earcup grille, and examine the cable along its full length, paying particular attention to the earcup exit and the plug, the most heavily flexed areas.

A final precaution is to identify precisely the impedance of the unit in question, since the three versions look alike from the outside: plugging a 600-ohm unit into a modest source results in a flat, lifeless sound, even though the headphones themselves are not at fault.