I can order (what we like to do on Headfi ;-)) a din to minijack cable, but if that's not necessary...
I have no opinion on that. I don't believe my neutralness detector is functional as they both sound pretty neutral to me.
Actually the X3's amp is the slightly more powerful of the two (marginally).
According to the specs the X3 is slightly more powerful on the amp front.
270mw into 32ohm vs the X5's 255mw.
I have the X5 and just grabbed an X3 as well. It is a brilliant little player and the controls are IMHO better than the X5's. The hardware based bass and treble adjustments are also impressive. +2 on the bass with my HP50's and for my sound signature taste, is perfect. I got it as carrying around the X5+E12 is not always practical.
I'm so impressed with it that I have a little buyers remorse with regard to the X5 and E12.
Still, that's what happens when you discover Head-fi. You might start buying gear you don't really need.
Odd, we read the same stuff and I have it that the X3 is stronger than the X5. I do not understand why they would do this but I believe my X3 is stronger than my X5. If the X3 had one more card slot I wouldn't have an X5. I don't mind though.