There are differences between the AH-C751’s and AH-C551’s, however, as you’d expect for that £80 differential. The detailing isn’t quite as nice as with the AH-C751’s – the plug on the short cable leading to the earphones isn’t aluminium, it’s plastic; and there’s none of the lovely ribbed trim gilding the edge of each earpiece either.
And that acoustic optimiser isn’t quite as large with the AH-C551’s, resulting in a stubbier profile. Not that this is bad thing – far from it. The larger chamber of the more expensive phones may well make for better overall sound quality, but they don’t look great and they’re not the most comfortable in-ear phones either. In fact the shorter front to back measurements of Denon’s cheaper phones mean they’re more comfortable in your ear, and they’re also easier to position correctly. Even with the limited fittings (which didn’t fit my ears at all with the AH-C751’s) I found it easier to achieve a proper seal with these. And getting a proper seal is crucial if you want to get the most out of any set of quality earphones meant for your ear canals.
And once you do pop these in your ears, the most important aspect of any headphone – the sound quality – is likely to impress. I hooked the phones up to a Squeezebox and headphone amp streaming lossless Flac files to ensure a top quality source, and warmed to the AH-C551’s immediately. First up in the queue of music for the listening tests was Pat Metheney’s quiet, atmospheric and beautifully-recorded ”Map of the World” album and this showed off the Denons in a very positive light.
They have a very warm and balanced sound to them, but with plenty of dynamics. When Metheney plucks his strings, the sound explodes out into your ears with assurance and timing that’s surprising in earphones of this price. In comparison with the AH-C751’s, the sound isn’t quite as airy, realistic and crisp, but it’s still pretty good. I moved next to something altogether more demanding and gave the AH-C551’s a blast of Metallica’s 1980s classic, ”Sad But True”.
With the AH-C751’s this sort of music can sound tiring with too much splashy top end, but strangely with the cheaper AH-C551’s it’s much easier to listen to. That warmth I mentioned previously helps to balance out any tendency for over-enthusiasm at the top end, resulting in a much more enjoyable listen. And, by the way, the complex distorted guitar work elsewhere doesn’t descend into a muddle either.