@Tapeworm: concerning my point 2 (lock screen), I may have expressed it in an unclear manner. I meant the following:
when the clip+ is locked and its screen is off, in order to see the title/artist (which may happen if you fill up the 8Gb with mp3) you have to unlock it first, wait fr the unlock confirmation to disappear, read the info and lock again. Annoying.
I think it would be more useful if, when the clip+ is locked and the screen is off, pressing any key would bring up the default screen (title/artist/time) for a few seconds, and then go back to screen off. Even during the lapse of time when the screen is on, the clip+ would have to stay in locked mode. Said otherwise, you can press a button to see the title/artist, but you can’t do anything else (except unlock with the dedicated button).
I don’t see any drawback with respect to the current behavior: the clip+ stays locked and the screens come on with useful info.
As it is now, the creens come on with somehow less useful info: it’s not realy necessary to be told *every time* that you have to press and hold the button to unlock.
And uh, the headphone amp costs more than the clip+ 
On top it kinda makes the whole thing lass handy (extra box, extra battery, extra cables), even if I don’t doubt it also provide a much better sound quality.
@mags1230 : rockbox, yeah I’ve seen, but i’ts my first week with the clip+, I’d like to avoid screwing it up right away 
On top, it’s unclear if installing rockbox voids the warranty. But I’m sure I’ll give it a try 
MaX.