In the store the Parrot Zik sounded OK with bass reduction on and using Bluetooth, since Bluetooth was the only connection available there besides the music playing in the kiosk. But back at home, I determined to use it with the headphone cable only. The Parrot Zik with noise canceling off sounded genuinely weird, as though there were a large echo and the details were very distant, at full volume. With the battery charged and noise canceling on, the sound came alive but was very, very bass-heavy. Setting bass reduction on, the sound was not only quite warm, but the response very strong down to 15 hz. I have several headphones with significant response at 15 hz - the v-moda M80, Sennheiser Amperior, ATH M50, Philips L1 - but the Parrot Zik dwarfed all of them at 15 hz and this was with bass reduction on for just the Parrot Zik. In this case there was no mistaking the 15 hz fundamental - whether by tone or weight, it's quite powerful and distinctly 15 hz.
With bass reduction on I would regard the overall sound as quite warm and having a strong bass, comparable to the non-EQ'd ATH M50 or Sennheiser Amperior to name a couple of popular headphones. Unfortunately, there was such a large peak around 6 khz that songs such as A-Ha's Take On Me had massive sibilants where sibilants should not occur. The 6 khz peak was not the only problem - I got the sense that the music was getting some kind of interruptions, and this was with Bluetooth and Wi-Fi off (iPhone4s with 3G only). Those micro-interruptions (for lack of a better term) were more obvious when running various test tone sweeps. I tried quite a few more music tracks, but eventually gave up due to the harshness that pervaded most of those tracks.
I'm aware that Apple has 'Apps' which provide some kind of sound retuning for the Parrot Zik, but I decided not to try those since this headphone has to work in the same environment with the other headphones and amps I have, and I don't expect that those apps would suppress the 6 khz peak without making other negative changes as well. Physically the Parrot Zik feels slightly heavy and mildly claustrophobic (with noise canceling on), but very comfortable due to the luxurious earpads. The narrow and lightly padded headband could cause discomfort unless users are able to put most of the weight onto the earcups, relieving the headband from having to support that weight.