So the 400s IS the right comply model for the N4. That's great! But which ones should i go for? The Isolation Plus or the Comfort plus? I am not sure which size to go for, but medium is probably the best choice for me. If only there where a size between medium and large...
The TS 400 that I have are the comfort model… first time I bought the mix bag (1 pair each of S/M/L) from Amazon.it, then, once I understood what size was good for me (as I said, actually 2 different ones, one for each ear, lucky me ) I restocked only the ones that I needed, maybe you could do something similar?
Oh, and from Amazon.it I supposedly originally bought the TSX-400, but they were really TS-400 (difference being in presence/absence of wax guard - mine do NOT have a wax guard).
Hope that helps