Okay, first a little on the M-Duo's. They are a little sibilant. High hats in rap are a little hard to listen to at high volume for too long. I had to turn down the hardware treble setting on my X3 a couple notches, which smoothed it out quite nicely. Bass is good on 0 setting, and really good on 10 setting. You can feel the air move in your ear canal, giving you a little tingle down your neck, it's cool. Reminds me of the JVC SZ-1000 over ears I had, with great head-shaking bass.
As for construction, the wire is nice. It's soft, and resistant to kinks or tangles. Has a universal mic and one-button remote on the left ear wire, I haven't tried it yet, but I'll give it a try on my XBoxOne, to see if the mic works. If so, then android is covered, and plastered on the box is iPod/iPhone compatibility. The looks are great. Metal earpieces that are light, and easy to insert, and are comfortable on long listening sessions. They aren't heavy at all. Right now, I'm using the supplied silicone tips, as my Comply tips haven't shown up yet, but I prefer Comply's. My feeling is that they will improve the sealing and give even more bass feeling.
As a comparison to the Atrio Mg7's that I currently own, well, I'll give my less than professional comparison. The M-Duo's bass is more "feeling" to it, like a physical sensation. The Atrio's, the bass is there, in copious amounts, but you don't "feel" it. As for looks, there's no comparison, the M-Duo's win that hands down, with they're sexy metal housings compared to the plastic build of the Atrio's. Sound wise, the Atrio's have a bit of an edge here, only because I don't have to tame the sibilance of them with the hardware treble controls on my X3. I have the treble setting at 0. The M-Duo's, I have to turn the treble down 2 notches, just to keep the treble in check, so as not to get tired listening to them. The M-Duo's sound good, but I have to give it to the Atrio's here.
Personally, I'm keeping the M-Duo's, and the Atrio's. I'm going on a trip soon, and I'll bring both, and give them a real workout on the total 12-hours of flying that I have to look forward to. This will also give me a better impression of which blocks more noise, and can be turned louder without annoying the person beside you. But I'm impressed with the M-Duo's, IEM bass has definitely improved since the 6-years that I bought the Atrio's.