I upgraded my Sennheiser HD 660S2 wired headphones with a more powerful iFi DAC to unlock the highest quality audio — but I honestly wasn’t expecting these results

Sound quality is important to me.

Whether I'm listening to hi-res mixes on Tidal or making music of my own, I want to hear it in the absolute best detail I can.

That's why, during Prime Day this July, I finally pulled the trigger and bought the Sennheiser HD 660S2.

But since then, I've started to wonder whether getting a DAC is essential to unlocking the loftiest realms of sonic sophistication.

While the Sennheiser HD 660S2 aren't the most expensive headphones I've ever owned, I'd argue they are the most premium, sonically speaking.

Compared to wireless headphones where a decent chunk of your spend is going on Bluetooth chipsets, ANC and fancy features, wired headphones such as the HD 660S2 are a pure audio play.

Pretty much every cent you spend goes towards their engineering for sound quality.

As a result, it's not surprising that my initial response to these cans has been positive.

They don't have the most strongly flavored sound profile — for example, there wasn't throbbing bass pounding my ear drums like Neil Peart trying to slaughter a fleet-footed fly crawling across his skins.

But their frequency balance is as judicious as any of the best headphones , neglecting no part of the spectrum.

Another huge factor is their open-backed design.

As they let in near enough every perceivable external sound, the idea of using them on the subway brings me out in a cold sweat — ain't nobody there to hear fellow passengers discuss nasty medical ailments in graphic detail before breakfast.

But that same transparency gives them a seriously spacious sound that allows each element a decent amount of room to breathe, already making them a great upgrade over their closed-back cousins.

Perhaps the biggest win in their corner is the very fact that they're wired.