“official”?   “Linux supports UAC2.”

Both are transparent.

    All the magic smoke got let out of that chip.   Good news: you get to buy yourself a christmas present, a shiny new sound card!

Yes; the STX II base card is exactly the same.

The are several different GX620 models; yours looks like "Desktop" or "Small Form Factor".   Anyway, you'd need a low-profile sound card, such as a Xonar DG/DS/D1.

  No; the card's DMA controller does not support moving data in a format suitable for DSD.

That "usb_set_interface failed (-71)" definitely indicates a hardware problem.

So "hanging" means that nothing is shown on the screen? This is normal (except for the missing sound).   Google says others have the same problem, but only with Intel USB controllers, and that the device forgets its own name (see "lsusb -v"). This points to a hardware problem.

What kernel version are you using? Those various players, do they hang too?   Are there any error message in the system log (see (/var/log/messages, or the output of dmesg)?

    For the effects of heat on the sound quality, see page 12 of the PCM1792A datasheet.   The card itself should work fine. None of the card's components are run near their limits. (Compare with a CPU or GPU: 192 kHz is 0.000192 GHz.)   If you want to improve cooling, remove the...

From what I've heard, the microphone input has not changed (i.e., designed for nothing more than VoIP or Karaoke).   Use your own mic preamp connected to the line input.

Galaxy Far East Corp makes the Tenor chips.   There is an official specification for high-speed USB audio devices (USB Audio Class 2.0, which is not the same as USB 2.0), but according to their website, the Tenor firmware does not support that and requires a hardware-specific driver. What you...

    The Xonar DG uses the CMI8786, which is a relabeled CMI8788. The Rosewill 702 uses the CMI8768, which is just a CMI8738 with two additional channels.

  The driver has been merged into the upcoming 3.11 kernel.   Quote:

This sounds as if the amplifier does not get enough power. Check the power connection.