I finally managed to do a little more testing after my post below. My results are that I am still seeing stuttering. What initially fooled me is that when playing a DVD ISO that always stuttered badly in a known section of the film no longer does so. However, on trying a few other titles I am still seeing the stutter in various sections of the video and therefore still disappointed. I cannot determine if the listed fix of: "System: Fix playback stutter issue cased by Wi-Fi" has made any difference to how I use the A5. I have also re-tested the playback of Big Buck Bunny 4k video I downloaded from http://4kmedia.org/big-buck-bunny-4k-demo/ and the audio is still several seconds behind the video. Has anybody else noticed this? Perhaps it's a problem with 4K MP4 files or just how this particular film was encoded? . . . I need to confirm my initial impression, but just have not had the time because of recent events in my life. However, I did notice this comment in the fixes: System: Fix playback stutter issue cased by Wi-Fi I am not sure if this is referring to the DVD stuttering or not. But then I wonder why it does not affect the playback of Blue-rays, MKV's etc. I only briefly tested with a title which I knew stuttered badly but did not watch the whole video, so cannot yet be sure if I am seeing a real improvement. Maybe this Wi-Fi induced stutter was the cause, I do not know. As said in the original post I need to test more.