This is probably irrelevant, but worth to try. Have you tried using a different sdcard on the X3?

I'm sort of expecting a different answer. But now I really have to checkout an X3ii :confounded:

Nice one! Have you tried clipping it on your shirt? Is it too bulky for it? The thing is, clipping on my shirt is the best way for me to get rid of any cables that may tangles.. also the most comfortable way using it while moving around. Colorfly C3 is 100g and I thought it would be too heavy...

You sir, are my greatest inspiration of April 2019.

Thank you for the research, it does seems that a perfect lipo replacement for Colorfly C3 would be a 1000mah 434350 3.7v lipo. https://cdn.head-fi.org/a/10249635.xlsx But looking for a fresh lipo battery in my country is a pain, except for some common sizes. So I agree that getting a regular...

Well C3 sounds very flat and "correct". Almost the same signature out of my DACMagic. I assume the Westone sounds very flat? If you want coloring, get V colored IEMs such as VSonic or as suggested, get an amp to do so. I myself found that it drives GR07BE pretty well on moderate volumes but out...

  Yeah the power issue is just a guess anyway. I really wanted to put the capacitor hack but couldn't afford losing the one and only C3 I had lol

Well it is sporadic in my Evo 128GB. Once every 5, 10 minutes, short ones, 2 seconds-ones, 3 seconds-ones. Yet no such issue at all with both Evo 64GB I owned. I don't think seek reading a memory card will require more power, though. It may not like spinning a disc faster or something like that...

As my guess is power issue, probably undervoltage or undercurrent due to the demands of some microSD cards, I am always thinking whether soldering a capacitor on the microSD slot power pins would cure the issue.   Apparently we have something here: http://forum.arduino.cc/index.php?topic=58643.0

  I think at this point you better stick to any well-tested microSD cards discussed in the thread. Get an Evo 64GB and you'll be fine.   Audio quality will always be the same but that buffer underrun stutter is what messed it.

  False hope. What a dissapointment      You're getting buffer underrun on a 32GB microSD card??? In that case I'm pretty sure this is some kind of power-related issue.   Switch to Evo 64GB and I'm sure the issue will go away. It's just that we haven't tried any "working" 128GB yet. If...

Custom version 1.4??? Where di you get that? Firmware alone could possibly fix the problem, really. I'm excited now