To begin with, I will state these were pre production units given to me for my opinion on how they sound, but the final production versions don't differ in any noticeable way. I've tested these using my combination of FiiO portable players and my Rockboxed Sansa Clip, as well as my Samsung S7 Edge phone using Poweramp. I've also given these a go in my home music studio for recording. Over 200 hours of burn in preceded this review as I've had these for a few months now. Here are the specs for those interested:Drivers: Dual balanced armatureRated Impedance: 30 ΩFrequency Range: 12 Hz ~ 26 kHzSensitivity: 110dB at 1 mWCable: 1.3 m Y-Cord, Over the ear, OFC CopperPlug: 3.5 mm, Gold plateI've been a Brainwavz fan since the very beginning as I've always liked their great value for the money spent proposition. Their B series continues this, but the top of the line B200's take the line in a bold direction, with dual armatures (that means dual speakers per bud, both tuned to work well together) plus very high quality with no compromises at all--all at a much lower than expected price point as IEM's that can do what these do often cost twice as much or more. The build quality, even on my pre-production units, are top notch. The OFCopper cables are thick enough with a casing that all but stops dreaded tangling in it's tracks. This is great if you regularly do a quick bunch up and stick them in your pocket as they easily spring back to shape in seconds. They have a built in pre-formed ear hook on each bud to also help facilitate a quick over ear hang that is very comfortable and convenient while helping to eliminate cord based micro-phonics. The built in slider also helps with the fit as well. I've used these for up to 8 hours straight with zero fatigue, both in fit and sound. They come packaged with three sets of hybrid silicone ear buds (S-M-L) and a single set of high end Comply T-100 memory foam buds, my personal favorite for comfort and noise isolation. It all comes neatly packed along with a cable wrap and shirt clip in Brainwavz excellent oblong carry case for easy portability and storage.The sound signature is one that will have it making many friends, as it's not tuned to blow your head up with powerful bass, or cause pain with harsh treble, or wash out vocals and instruments with distant mids....in fact these are the first in ears I've used that really make a case for being near professional level monitors. The signature is dead neutral to my ears, with no coloring of the source material that I could detect making these a great asset to me while recording and mixing my guitar on my computer. The sound stage is plenty wide enough to allow for hearing great detail and position in even the most demanding music. Operas soared to my ears, truly sounding as though I were there in person hearing every single sound from orchestra to vocals with no wash out or loss, a really fantastic experience not usually found at anywhere near this price point. I found myself playing back songs I've heard a thousand times again and again simply because the B200's were allowing me to hear details I've missed in the past...again, a very rare thing at this price point. To sum up, if hearing your source material the way it was meant to be heard from the creators of said material, with no coloring or change at all and with amazing detail, the B200's are your IEM's.I must say that the B200's caught me a bit by surprise. I honestly didn't know what to expect when these arrived and I was thoroughly blown away by it's build quality, and more so by it's sound signature. It is really hard to find good in ear monitors at any price much less what these cost. Being a musician I'm always on the lookout for in ears or over ears that allow me to record with no coloration at all, with great unhindered detail, something that's a hard find for under $500.00 much less what you get here for under $200.00. My thanks to Brainwavz for accomplishing this for us not so rich folks, it's really appreciated. Very highly recommended!