Denon AH-C751 sound-isolating earphones review

Whether you're upgrading the earphones that came with your MP3 player, or upgrading the £60 'phones you invested in initially, Denon's £150 AH-C751s could be a stonking entry into high-end earphones, if they're anything like their predecessors, the excellent AH-C700s.

As sound-isolating earphones, they aim to passively block out ambient noise around you without the electronics involved in noise-cancelling headphones. But are they worth £150?

Strengths
Sturdy aluminium enclosures make these a weighty but robust pair of earphones, with decent cabling and a detachable 0.8m extension should you only need a short wire. Every connection is gold plated to ensure you get decent audio performance, and a lovely sturdy carry case is supplied to keep things safe when not in use.

When they are in use, you'll notice the sound isolation -- provided by soft silicon tips on each 'phone -- is fairly good, and a range of differently-sized tips are provided to ensure you get the most comfortable fit.

The importance here is placed on sound quality and, as with the previous C700s, we're pleased to report it's superb. The C751s demonstrated an ability to produce beautiful highs, punchier mids than the C700s, and the same smooth, deep bass we loved so much in their previous incarnation, with a response range of 12-24,000Hz backed by Neodymium magnets.

Tool's complex track Ticks & Leeches from the album Lateralus was the first to show just how capable these earphones are. Danny Carey's drum-only introduction utilises not only interesting usage of the 7/4 time signature, but also an array of beautiful-sounding drums, each resonating with smooth tones and hard-hitting mids. When the double bass drums kick in, nothing is taken away from this sound; only pounding bass is introduced, along with notably bright cymbals and that crunchy distorted guitar track.

Moving onto some hard-hitting club tracks, Mark Knight's beautifully dirty track -- featuring the luscious Luciana -- Party Animal demonstrates the C751's ability to handle the kind of bass lines that make ears bleed. No earphone we've heard at this price gives dance fans this level of boom for their buck. That they excel with mids and highs equally well speaks volumes about the audio prowess of these 'phones.

Weaknesses
Compared to Etymotic's sound isolation in the hf2 and ER-6i earphones, the isolation of the C751s is less impressive. It's a huge, enormous heap better than 'phones without silicon tips, but the C751s failed to block out as much noise as the flanges produced by their competitors. However, with music playing, it's still very good, and will make a huge difference to your enjoyment of tunes on the commute, just not quite as much as Etymotic's isolation would.

Although they're comfortable, the C751s are quite large and weighty, and absolutely not suitable for use in a gym or when running for the bus. They're ideal for listening at home, when sat on public transport and indeed in most other applications. If you anticipate yourself moving an awful lot while listening, you may prefer smaller, lighter weight offerings, such as Jays' q-Jays.

Conclusion
A great follow-up to the AH-C700s, the AH-C751s offer a slightly punchier mid-range without taking anything from the lows or highs. Compared to Shure's similarly priced SE420s, they offer a cleaner sound, with better emphasis on high-end detail, although the SE420s are arguably a little more comfortable.

If you want a slightly rawer, meatier sound, do consider the SE420s -- with twin drivers in each ear, they're capable of giving you more impact, though you'll sacrifice the absolute crystalline clarity of the C751's treble and bass.

Edited by Jason Jenkins
Additional editing by Shannon Doubleday