Issue: PLL staying active.
To avoid getting a unit that falls apart or has poor internal soldering, buy your CX31993 dongle from recognized budget audio brands such as JCALLY (e.g., the JM6 or JM7 lines), Abigail , or GraveAudio . JCALLY JM6E CX31993 DAC - Reviews - Head-Fi cx31993 datasheet fix hot
If you are driving 16-ohm IEMs at high volume (30mW output), the chip might draw 90mW from USB. The 30mW difference is heat. But the "fix hot" issue arises when idle current jumps to 300mW due to a design flaw—leading to 200mW of waste heat inside a tiny 5g metal dongle. Issue: PLL staying active