Also noticed this sibilance talked about earlier on a few occasions, but again I'd blame the recording and not the speakers.

A particular striking and quite obvious example:

Ex: http://www.youtube.com/watch?v=zMPIbx6SU5o
1m40

I hear it too on my comp setup, but at a lesser level as the speakers are much less revealing...

I'm no recording engineer, but I believe it's due to the microphone, you often see artists in studio using a sort of 'disk' in between themselves and the microphone, I bet they didn't use one or used some poor mics or something...

Ah yes, quick google:
Sibilance is the term for harsh "sss" or "sh" sounds in a vocal recording. There are a few ways of dealing with the problem:

Before recording: Look for microphones with a "flat" response, which tend to suppress sibilance. Many high-end vocal mics deal with the problem with larger diaphragms and other built-in components that moderate these specific signals. You can also run the microphone through signal processor that features a "de-esser," which you can adjust to cut sibilance.

During recording: Experiment with the microphone's position relative to the speaker/singer. Often backing the microphone away a bit, angling it down, or having the person sing slightly to one side of it will reduce the sound energy that's causing the sibilance to begin with.

After recording: If your vocal track features too much sibilance, you can use sound editing software to reduce it. Be careful, though - just cutting the sibilance frequency (around 8 kHz) across the board can deaden the sound of the track. For optimal results, identify the specific areas on the waveform which sibilance is a problem and selective cut the 8 kHz volume in those areas.

Remember, too, that your sibilance problem will be different with each performer. There's no "one-size-fits-all" solution for every recording situation.
Again, it's not because you hear something on some speakers that it's invariably a flaw of that speaker... Now I'll admit that on my different setups (headphones, speakers), it's definitely most obvious on the NrTs, but at the same time the NrTs are my most resolving playback device... But since the big majority of recordings sound ok and only a few seem to stick out like sore thumbs, my take is that recordings are much more at fault than the speakers...