Raz was kind enough to send me a set of Brainwavz M4 iem's to review a couple of weeks ago - and due to vacation, this is the first time I've gotten a chance to write up my review. This will be my first time writing a review (I think) without having read other people's opinions - so I'm curious to see if others hear them the same way. If my review deviates from the norm too much - you might be able to tell that I'm full of it.
I went into overkill for burning these in since I was so busy with work - I was unable to do much listening at first. I just connected them to my computer and had a random playlist (24 gigs of assorted music) going non stop for about 150 hours. For burnin - I typically play music a little louder than I would comfortably listen to.
The Hardware and Fit - My original impression of seeing the pictures online was that they seemed to use a cheap simple plastic housing used on many other cheap IEM's. In getting them, I thought that was far from the truth. The housings are solid, and well built - they look really good in person. These IEM's are very light and fit very well - I had no issues with sound isolation. I tend to avoid the foam tips - so I used the rubber flange tips that came with the M4's. I also did some listening with sony hybrid clones. After hours of listening - I could scarcely tell they were there.
The cable was a mixed bag. It looks and feels great. I have no concern that the cable itself will be durable, and it has a nice color mixture that you may have picked up in closeup pictures. The only concern I have is that it seemed to be more microphonic than usual. I thought this was the case whether I wore the IEM's facing down or over my ears. The shirt clip (included) was useful. A "chin strap" (which was not) might be useful as well to prevent further motion. Overall - for desk listening I had no problems - I didn't particularly like the feel/sound while walking.
The Sound - The bass is great. There's not as much bass as the M2's but there's still a good quantity. Only hard bassheads would be disappointed I feel. The bass is accurate and punchy, and unlike the M2's doesn't bleed into the higher frequencies.
The mids are detailed and neutral. Not as warm as the M2's, probably because the bass doesn't intrude. It may not be that the iem's or driver are more detailed - but the lack of bass intruding allows you to pick up more intimate details than you would otherwise. I say neutral because the mids don't get the impression of bringing the singer in needlessly closer. The soundstage is pretty great for IEM's of this price.
The treble is of a very good quality, and has a good amount of detail about on par with the mids. The one thing in the sound signature that left me wanting a bit - was the extension. The treble rolls off gently at the top. But it's not too bad - even though I'm generally an analytical listener and love the treble in more expensive IEM's like the Re0 and TF10. I think these IEM's may have benefitted from a silver cable like on the M2's or M3's (though I guess it's possible the cable is already silver - I've intentionally avoided specs and reviews). Based on the sound signature, the cable might have given these that little bit of extra treble some might want.
Comparison - I keep arguing with myself over whether these are my favorite mid-priced IEM's or not. It's either the M4's or the M2. The M2's aren't as neutral or detailed as these, but have that heavy bass and warm mids that makes them unusual in comparison to other IEM's in their price range. If forced to choose - I think I'd purchase the M4's. At a price/performance ratio - I would much rather have the M4's than the M3's.
Compared to my old Sennheiser CX500's others may have heard, these win hands down in just about every category I feel.
In short - the M4's are excellent IEM's that I'd be happy to give as a gift or recommend that others purchase. Please let me know if I'm way off base on any of this review - I'm curious to see what others think by comparison now that I've written this up.