There's too many mixed opinions on here, can't decide whether to get a Cowon S9 or an iPod touch 2Gen (Probably 3Gen when released)
Simply, which has a more richer, fuller sound when using headphone out (No EQ)
Just chiming in but...
Personally, if you want just pure audio quality through the headphone out, I would get the S9. If you intend to get a amp, you could still get the S9, but I think coming out from the LOD, the Touch is better, but that's just imo from the listening sessions I've had with a friend's S9. All flat EQ by the way...no EQ, BBE, or MachBass.
Had this same problem, got the S9. Totally satisfied. I decided I wasn't getting an amp a while back because it just makes life more complicated. Like I would only get the touch because of the ease of use and if you get an amp, your making it a lot less convenient. Plus it takes the price of your gear way up. Also, I think its missing the point when you compare the S9' sound quality on the "normal" setting. Once you try the presets, or make your perfect EQs, you'll never go back to listening without it. Seriously, neutrality is overrated. As stated before, BBE Viva and BBE Headphone are really great, and there's like 26 others. And the guy who talked about the EQ was talking about a completely different device, the D2. That's like me trying the iPod nano and saying I was dissappointed with the Apps. There is a seven Band EQ with 24 volume settings for each band, plus you can choose one of five frequencies per band. Then there are two other screens full of effects, including BBE which is a professional sound enhancement, Mach3Bass, 3D surround, stereo enhancement, etc. You can save up to 4 presets - basically, you have complete control over the sound. Expecting every headphone to perform well with the same sound (iPod Touch) is just crazy. You can customize the sound completely with the S9. And it never sound unnatural or anything, unless you put all the effects up to ten. And don't listen to the guy with his "lab research" and "legit science" about sound quality. You can't prove sound quality in a lab or with graphs. If I thought that was true, I never would have bought my IE8s, which I love, because the frequency response graphs show that its far from neutral. Everyone can agree that sound is completely subjective. But if you get the Touch, your limiting yourself to one sound (disregarding the crappy eq) while with the S9 you have endless possibilities. I doubt anyone would like the sound of the S9 on the default settings, because the S9 is all about customization. So do you want to be part of the crowd, or do you want your pmp to be all about you? The choice is yours.
Oh yeah and on the subject of matching IEMs to players, you want a brighter-sounding player if your getting darker IEMs. The S9 goes perfectly with my IE8s because the IE8s are bass-heavy and the S9 is less so. So if your getting SE530s, take into account how people describe their sound. If they're described as dark or bassy, the S9 would make a great match.