hey rovopio you can call me arghhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh(short for castleofargh), we're buddies by now ^_^.
ok the crosstalk doesn't really matter. we're most of the time, at levels where people are not likely to be able to notice a difference. I just mentioned it in the middle of other possible improvements I could think of on the top of my head, because it is easy to measure and so represents a factual improvement of sort. and why I mention it, well it's just that most DAPs when confronted to low impedance IEMs (like 16ohm or below) will tend to have more crosstalk, that's a fact. I'm guessing because more current flows into the circuit so maybe more induction effects and possibly other reasons that I don't know about because I'm not an engineer.
still you can often observe this when looking at measurements values into different loads for DAPs or amps. and the A15 is a perfect example of this.if only the headphoniaks had posted their review before mine so that I could leech on it and pretend that I know stuff ^_^. http://headphoniaks.com/blog/sony-walkman-a15-analisis-tecnico-y-review/ look at the crosstalk readings into different loads(impedances). they're soon below the first pictures in the summary of measurements.
a nice amp able to deal with a 16ohm IEM will tend to have better crosstalk(and most likely better many things). so bypassing the amp of the A15 for that better amp, we will de facto improve the sound fidelity in a few domains. that's why I'm so pushy about amps when it comes to people who want only the best sound(because for others it's just another bulky brick to carry around).