Finding a really good pair of on-ear headphones can be a challenge. While they're more compact than over-the-ear models, they often aren't as comfortable -- they sit on your ear after all -- and don't measure up sound-wise to their over-the-ear brethren, which also tend to do a better job sealing out ambient noise (at least the closed-back models do anyway). So it's easy to get excited when you come across an on-ear headphone like the Beyerdynamic T51i that not only features top-notch sound but is sturdily built and comfortable to wear. It's priced at $300 (£190 UK, AU$400).
Made in Germany, the T51i is a dead ringer for Beyerdynamic's earlier T50 (now discontinued), but the newer model has upgraded innards and sound.
The big difference between this model and the now-discontinued T51p, which we reviewed earlier, is the inclusion on a three-button inline remote and microphone that's designed to work with Apple's smartphones and tablets and may not fully function with Android or Windows devices.
The relatively lightweight (174 grams) mostly metal design doesn't have a hinged headband, but the earcups fold flat for easy storage in the supplied, well-designed carrying case.
Those earcups are padded with memory foam and they sit on your ears snugly without applying too much pressure. The headband conforms to your head nicely and doesn't leave a big gap in the temple region like a lot of headphones do. It's a comfortable headphone to wear for hours at a time without experiencing listening fatigue. That said, the cold metal design isn't for everyone and those with larger heads may end up with the metal part of the headband resting too close to their heads for comfort.
Isolation from external noise on the New York City subway was decent, though not up to the standards set by noise-canceling headphones and some over-the-ear models. Then again, the T51i sounds better than any of those headphones and it doesn't need batteries (all noise-canceling headphones do). While most audiophile headphones come with one-year warranties, the T51i's runs two years.
Impedance is rated at a highish 60 ohms, but the T51i sounded great plugged into both mobile devices (iPod Classic, iPhone 5S and Samsung Galaxy S5) and a Schiit Asgard 2 headphone amp at home.