We used the MDR-1RNC a number of weeks, in order to properly break them in. We played music from a number of different sources, including PCs, smartphones and mp3 players. We also tried different types of audio files with varying levels of quality in addition to our standard test suite. This gave us a good overall impression, which in the case of the MDR-1RNC is generally positive with a few exceptions.
These headphones appear to be aimed at the general consumer. The sound is accessible, with a slightly emphasised low-end for some extra punch. This can be distracting in some genres, such as classical music and jazz, where certain instruments will dominate too much. The equaliser will solve this if it bothers you. For most mainstream genres it produces an appealing, lively sound, and the fact that it's not 100 percent neutral isn't a drawback.
We do miss some volume in the real low-end and sub-lows, depending on the audio source. Sony claims an impedance of 24 ohm by 1 kHz, which could explain why in combination with certain portable music players it struggles to do justice to the entire frequency spectrum. The iPhone 4, known for not having the best audio codec and line out, sounds relatively flat. The previously tested P3 van Bowers & Wilkins did better in that regard. When we connected the MDR-1RNC to a high-end audio card with integrated headphone amp, the sound is significantly better, but also the new iPod Nanon sounds a lot better, with convincing bass, clear highs and a dynamic sound.
The MDR-1RNC does a good job with lower-quality audio files. Sony claims they use sound-enhancing technology for restoring and 'massaging' compressed waveforms, and it does make a difference when you listen. It removes the sharp edges from low-bitrate mp3s, but of course there are limitations to what it can do. A terrible recording won't sound perfectly amazing, because there just isn't enough data there. It's always best to use the highest-quality audio files, at least 256 Kbps mp3 files, but preferably even higher quality.
The noise cancellation technology employs two separate microphones and works really well, on the same level as the Bose Quiet Comfort 15 which we see as the benchmark in this category. Sony gets very close with the MDR-1RNC. We tested this feature in a number of different environments, in the office, on the road, and even with a jackhammer on the other side of the wall. As soon as you turn it on, there is a very significant reduction in ambient sound that you can hear. It works markedly better than on the similarly priced Sennheiser MM-550 X Travel.
It does change the sound a bit of the music you're listening to, but it's something we can live with and definitely prefer over noisy surroundings. Nevertheless, the bass is less present when it's on, and that already wasn't a strong side of these headphones. Another side-effect is that the sound of the human voice is distorted, almost as if helium was ingested. That does take a little getting used.