Like the rest of the series, the MDR-1RC screams solidity. The plastic/metal body is on the large side, but it's well made. The headband looks practically unbreakable and the design is tasteful, sober, classy.
The padded headband is comfortable, but the outside lining looks a little fragile and could potentially degrade with time, a problem that does not, however, affect the foam-covered earcups with their thick, artificial leather lining.
The active noise cancelling button and micro-USB connector are built into the edges of the earcups, both discreet and effective. It may take a second to find the ON button for the first time, but once you know it's there, you know it's there.
The accessories are as follows: one conveniently compact, semi-rigid carrying case (the earcups pivot inward so you can lay the headphones down flat in the case); two detachable cables (one smartphone cable, one regular); an airplane adapter; and one USB cable. There's no wall charger, but you can always use a smartphone charger instead. The battery lasts well over 20 hours with each charge. The MDR-1RNC does not come with a 6.35 mm jack adapter.
Sony clearly made the right choice by giving the 1RNC effective noise cancellation in both active and passive mode, a boon for a headphone with a battery like this. The only problem is that the frequency response varies wildly between both modes.
Frequency response: passive noise cancellation
Using the passive noise cancelling only, the low-mids are what stand out (see where the low-mids meet the low-end on the curve), giving a nice, meaty sound that unfortunately is counterbalanced by the lack of impact in the deepest lows. The overall curve is perfectly respectable, although we would have preferred more volume in the top end of the spectrum.
Frequency response: active noise cancellation
In active mode, it's the exact opposite: that bump in the low-mids disappears, only to reappear in the lowest end of the spectrum. The difference is palpable, doubly so because the overall volume goes up in active mode. The soundstage gets beefed up with the active cancelling on, but the rendering becomes surprisingly harsh.
Left: THD+N as a %. Right: THD in dB.
The MDR-1RNC has relatively little harmonic distortion for an ANC headphone, but it's still a notch below the top dogs in the sector. And it doesn't hold out very long when subjected to square waves, which produces a dragging sound in the low-mids and at-times unnatural resonance. This is bizarre to see on an active headphone.
Last point, the isolation. When it comes to noise-cancelling over-the-ear headphones, Bose and Sennheiser are the ultimate references, thanks to highly effective passive isolation. In ANC mode the circuit on the MDR-1RNC creates a constant hiss. It's a shame—not only does the function ultimately miss its target, but it also considerably ups the price. Why buy a pair of active noise cancelling headphones when the active noise cancelling causes hiss?