Comment 47 for bug 1487168

https://www.virtualbox.org/changeset/55272/vbox/trunk/src/VBox/Devices/Audio/DevIchAc97.cpp

since it hardcode ad1980 on a dell machine, you may need patch in alsa driver to prevent the swap of the master playback volume/switch and headphone playback volume/switch

   if (fChipAD1980)
  {
        PCIDevSetSubSystemVendorId(&pThis->PciDev, 0x1028); /* 2c ro - Dell.) */
        PCIDevSetSubSystemId (&pThis->PciDev, 0x0177); /* 2e ro. */
  }
 else
 {
      PCIDevSetSubSystemVendorId(&pThis->PciDev, 0x8086); /* 2c ro - Intel.) */
     PCIDevSetSubSystemId (&pThis->PciDev, 0x0000); /* 2e ro. */
 }