Pros: Comfortable; sleek appearance; nice stock tips; A+ bass response; friendly cord; Exemplary customer/warranty service
Cons: Tight soundstage; no nozzle foam grille of any kind to protect drivers from provided cleaning tool
I owned several pairs of the M5s (owing to the fact that I had them replaced several times through the warranty service). Never had a lick of trouble getting a replacement. I bought from an authorised reseller on fleaBay for a very decent price.
The design of these IEMs is quite pleasing to me. They are low profile, nice blue accent, sleek design. The cable is not at all fussy. The provided rectangular case is of a good size as well as quite durable. My package included a very nice assortment of tips, single through triple flange of 2-3 sizes each. Sure olives fit these IEMs as well.
I found them to be very comfortable for extended use using the stock biflanges. The olives I have provided a tiny bit more isolation, but I felt the isolation was good enough for my needs with the biflanges and the olives hurt my ears with extended use.
The sound...as many are aware, the bass response of these is quite renowned, and for a very good reason: excellent sub bass extension, quick, punchy, and full sound at low frequencies, and very little bleed into the mids. I wouldn't say the mids are necessarily recessed, although perhaps lacking a bit of detail or attention-grab from a more mid-centric IEM. The highs live in a similar boat, not forward yet not at all lifeless. These are not a 'sparkly' or 'bright' sound by any means, however I would not say the sound is extremely dark, either; rather, it's a decently flat sound with a warmth to it.
The soundstage, owing to the lack of shimmer on the high end, is a bit tight, although it has some decent depth. Despite the fact that things are quite 'intimate', I found the separation admirable.
Overall, the character of these IEMs is warm with EXCELLENT sub bass extension and terribly accurate and engaging bass response, with a pretty warm overall presentation and a fairly small 3D presentation. The upside is that you won't find bass like this anywhere else close to it's price range, and the presentation is not at all fatiguing. The downside is that it passes up a bit of detail and shimmer.
Future Sonic's warranty and customer service is absolutely wonderful, I might add. In the end, though, after tons of abuse, my 3rd pair of M5s bit the dust I believe because I may have stabbed the right driver with the earwax cleaning tool provided - there is no nozzle foam or grille between your eardrum and the driver on these, so use caution. This may be what the Atrio M5 owes a bit of it's amazing bass reproduction to.
All in all, an excellent value, and although the MG7s have now usurped the M5s, these were fabulous IEMs.