I reformatted that card in the exact same way I have formatted all cards used with the X3ii, that is, in the X3ii itself.   It may have something to do with card compatibility. But the card I had trouble with was a Lexar Class 10 64GB bought at Best Buy, so it should have been okay.   Also...

That seems like a more than adequate amount of free space.   It's possible that the card itself might be the problem since your 64GB card seems okay.   I had that problem with Hi-Res files on a 64GB card. I then reformatted and loaded up some music. It worked okay but I haven't yet tested it...

How much blank space is on the card when you get the stuttering problem?

Good to know, thanks.

I've uploaded about 20GB of files to the reformatted (in the X3ii) 64GB card and tested it on the X3ii with no stuttering so far. Given my experience and what you are all saying, I'll leave about 10GB free space when I finish the full upload.   Thanks to everyone who took the time to give me...

Regarding #2, here is a link to the online English manual page for the Home Menu:   http://helpguide.sony.net/dmp/nwza10/v1/en/contents/TP0000428511.html   You'll probably find that manual of good use.   Re: #4, I have the HD598. They have a warm sound with the A17. I don't need to have...

I can't upload the image of the file INFO window (not here long enough, I guess) but it shows the capacity as "64.07 GB".

Actually I did format all my cards in the Fiio X3ii.   Anyway I just tried a different, smaller card, an 8GB that I reserve for FW updates, and which had been formatted in the X3ii, and transferred the stuttering file to it, and there was no problem. The album (James Brown All-Time Greatest...

That's exactly what I'm going to try.

I'm dealing with exactly that problem now: random stuttering with hi-res files. I updated to FW1.3 from FW1.11 BETA in hopes of resolving the issue, but it's still there.   I tried the same file in a different player and there was no problem.   Next I'll try a different microSD card.

A headline from the web:   "A quick spin around Sony's new £500 Walkman, the NW-ZX100HN #IFA15 #SonyIFA"   Could this be the price?

This is from the manual:   "(*2) Copyright protected WMA files cannot be played back."

  My ATH-M50S sound great with the A17 and the playback volume is 18 or 19.

Well, now I'm impressed with this little device.   I paired it up with my ATH-M50S and it is SMOOOOOTH.   Listened to "EVERYBODY DIGS BILL EVANS", a vinyl rip to 24/96 FLAC.   It's like playing an LP through some Dynaco A-25's. Very 1970's Hi-Fi, thick, not airy, but truly pleasurable...

I'll definitely give it more time.   I checked the settings and none of the "sony audio gimmicks" were turned on. But would using DSEE HX make an improvement?