Thank you Kamil! I haven't had the chance to test the M1, but from the few testers of them both, I get that the shape of the ZX1 definitely favours the sound. The M1 doesn't have enough room to make the bass stand out clear from the other frequencies. The ZX1 does… totally.

So even if you like the design of the M1 better, as I do, I'd still go for the ZX1.