X5 Stuttering issue:
I have posted on this thread about problems with the X5 "stuttering" or skipping when playing 24 bit high resolution Flac files. I can now report that the issue of the stuttering has been solved, although I'm not sure I would say the problem is fully resolved.
I have all my music in two 64 GB ADATA micro sd cards in my X5. There are about 3,500 individual tracks, all in artist/album folders. Most of my music is from CDs ripped directly to Flac on my Linux machine. Some of my music is 24 bit 96 khz and 192 Khz albums from HD Tracks, along with some DVD audio discs ripped to 24 bit Flac.
All of the ripped 16 bit 44.1 khz flac from CDs play perfectly on the X5. The sound quality from some of the well mastered CDs is quite stunning. But many of my favourite 24 bit High res files will skip or stutter randomly on payback. No amount of formatting or re-copying fixed the problem. The unpredictability of the stuttering was itself part of the problem - it became impossible to listen to some albums without holding my breath, waiting for the next glitch.
Finally, out of desperation I bought another micro sd card, this time a SanDisk Ultra 64 Gb. Both the old ADATA and the new SanDisk are class 10, but the SanDisk claims to have faster read and write speeds (at twice the price of the ADATA). I transferred all of the offending 24 bit High res files (and regular stuff) onto the SanDisk. I can now report that the stuttering no longer occurs with the same material on the SanDisk micro SD card.
Now this is the part I find interesting; I put the ADATA SD Card into my Blackberry Z10 phone and loaded the Neutron Music Player app (great program btw). All the high res files that were problematic on the Fiio play perfectly on the Neutron player using the old ADATA card. My tentative conclusion is that the Fiio has a limited amount of buffer memory and SD card read speeds can become critical when playing higher bit-rate recordings, my assumption is that the Blackberry/Neutron combo allocates more buffer memory and is not affected by the lower SD card read speed. The Neitron player reports the playback rate for recordings in Mbs (Megabits per second) A 16 bit CD quality Flac runs at 1.4 Mbs, whereas a 24 bit 96khz file plays at 4.6 Mbs, while a 192 Khz file is 9.2 Mbs. I would consider this to be a design flaw in the Fiio - for an otherwise great package intended to play high resolution source material, I would have built in more system resources, especially system memory.
My final observation - the Neutron music player sounds great!. It gives up very little to the Fiio; perhaps a little bit of clarity and definition and a line out, but it has a host of other features that are absent from the Fiio. One of those features that I have come to appreciate is the ability to choose and adjust crossfeed - this has a big impact when listening with headphones and it is a feature that should be added to the X5 firmware; unless somebody can figure out how to port Neutron to the Fiio.
