Ok, I've been using mine for the past few hours now. Now, they certainly sound very good. I'm by no means an audiophile, but I'd say they sound quite a bit richer than the FXD-70's (my previous IEMs, I will be using them as comparison here); just as clear, but still with a decent amount of bass. I want to preface this with a disclaimer: my first impressions tend to be quite negative and I'm usually way too picky for my own good, regardless of which IEM I've bought. With that said, my first impressions of the RHA MA-750i's are varied.
I've always had fit issues with IEM's since my right ear canal seems to be a lot smaller than my left, but since my FXD70's fit me quite OK with some foam tips I ordered from ebay, I figured I shouldn't really have any problem with these since the nozzle was of similar size. However, the 750i's have quite a pronounced conic shape whereas the FXD70 was just a tube. I don't know how deep the insertion should be with the 750i's, but I was a bit more satisfied with the deeper insertion I could achieve with my FXD70's. With a bit of twisting and turning it gets better, but still not quite there. They don't fall out (from what I've tested so far) - rather, they're just uncomfortably big for my small ear canals. I'm using the supplied foam tips. I haven't tested the bi-flanges yet.
Maybe it's just about getting used to it?
Or maybe I should've just gotten a pair of Etymotics from the beginning, hehe.
Perhaps someone can recommend me some good tips which are slightly smaller than the supplied ones?
The cable is quite thick and maybe a bit too rigid, but I think it'll soften with time and use. The FXD70's hade quite a thin cable, but on the other hand, they broke (although they lasted 1 yr & 9 months of heavy everday use without taking any special consideration).
I don't quite like that the chin strap is placed above the remote. I'd like for it to be able to go all the way up, but it's not a big deal.
However, I don't doubt that RHA has considered other possibilites for this and for some reason this was found to be the best one. I've never had an IEM with a remote before so I wouldn't know if this is a common solution or not.
The clip could be more easily adjustable but it's not a big deal.
I'm gonna use them for a few more days and then I'll see if I'll keep them or not, but they're definitely not bad IEMs. Just maybe not for me, I guess.