Ok......I'm starting a bit more critical listening. I did a fast A/B with my MS 1 and you know what.......the MS 1 might be the best deal going on a set of iem cans. Really, they sound f'in good. I can't believe I paid $60.00 for a pair of them. Initially, what I can say is that they are in the same camp tonally. Defined bass....not over ripe or bloated but firm, extended and articulate. The high end is clean and fast with a bit more shimmer on top when compared to the M1. The M1 is a bit drier. The midrange is even, where I think there might be a slight 2k boast on the M1.
The 400 are clean....without haze or cloudiness and fast. Snares have snap.....toms have weight and body......especially the floor tom. Over all there is nothing to complain about frequency wise. They are well balanced and do not cater to bass heads or treble heads exclusively. Although both should find something they like in them.
Where they outshine the M1 is in the soundstage width......sounds come out further both left and right. At the right volume they are more like listening to my highly modded 3A's with dual subs......coupled with tubes.
So in my limited world of headphones these have been my favorite on ears bettering AKG's 240, 701Q's, 550's........ATm50's, sennheiser 580, 600 and 650's, 280's Grado RS2's, SR80, 125's and Sony MVR something or others. And yes, they better my second favorite Thinksound M1's, but I'll be keeping my two pair of M1's for those noisy environments and outside the home travels.
One last thing...I find the fit is comfortable and they do not bother my head. I can listen for long periods of time without a problem. Nice cans, great value and fun to listen to. If your on the fence I hope I pushed you over.....I don't think you will regret it at all. Plus 1 for Razor Dog's open box price, too.
If anything changes I'll report back.....right now I have about 40 hours on them.