Denon is a company best known for its hi-fi components and DVD players more than anything else. It's won multiple awards for the latter and the firm's superlative 1920 player is my current movie player at home - until I stop being stingy and stump up for a Blu-ray player.
Something it's probably less celebrated for, however, is its headphones. This is perhaps understandable as it's an area it has only recently moved into, but for an upstart it has a remarkably wide range. Courtesy of a number of new launches, it now has headphones covering everything from the very high-end (the AH-D5000 and AH-D2000) right down to budget £30 canalphones (the AH-C351) with plenty in between.
We've already reviewed the firm's top-end canalphones, the AH-C751's, and were impressed by the sound quality, if not the fit and comfort. Now it's the turn of the more mainstream AH-C551's, which come in at £70. At this price, however, they're up against some stiff opposition. Sennheiser's excellent CX 95's cost around this much and are my current favourite mid-range headphones.
The AH-C551's make a good first impression thanks to their fine build quality. Like the AH-C751's, they're constructed from a solid, machined aluminium housing. They feel super-solid, cold to the touch and are pretty light at 5.4g per pair. The cable is robust and the joints at the earpieces and plugs are all well made. This is a luxurious, high-spec pair of phones that feel worthy of every penny of your £70.
As with the AH-C751s, the 551s have modular cables so you can use them with a mobile phone hands-free adapter or a clip-style MP3 player without having to stow away a tangle of wires. They come with a hard case and the same set of three rubber fittings - large, medium and small flanges - are included in the box. It's disappointing that more weren't provided, but it is relatively cheap to buy alternatives if these ones don't fit your ears.
The cable is impressively tangle resistant: stick these in a pocket and when you come to pull them out you're much less likely to have to spend the next five or ten minutes unknotting them. This is one area where Denon has Sennheiser beaten - the CX 95's cabling frequently becomes an impenetrable mess in my pocket.
The AH-C551s also sport a similar internal design to the more expensive AH-C751s: they're single driver phones with a small ported cavity behind the driver, which Denon dubs the 'acoustic optimiser'. This is supposedly to balance out the pressure that builds up behind and in front of the driver's diaphragm for a more natural sound.