This skin will give you all the information, and allow you to copy the values to the Windows Clipboard, so you can copy and paste those rather long ID numbers into your skin if needed.
Requires the latest Rainmeter beta 3.2 r2326 or later from http://rainmeter.net. Also requires Windows Vista or later. Clipboard:
Windows Default Output Device:
Device Name: Speakers (Realtek High Definition Audio)
Device ID: {5c106e65-26b4-4d05-a9bf-b207a71e9eaa}
Device Format: 48000Hz PCM 32b 2ch
Device Status: 1
Device List:
{2d89ffff-c125-43eb-baa6-e6c484865e74} Realtek Digital Output(Optical) (Realtek High Definition Audio)
{2f760934-76a8-4ff7-9562-e7d5293e3eb7} 4 - Digital Display Audio (AMD High Definition Audio Device)
{36c86755-6d3d-499b-9aee-5eb1155a17c6} 2 - Digital Display Audio (AMD High Definition Audio Device)
{5c106e65-26b4-4d05-a9bf-b207a71e9eaa} Speakers (Realtek High Definition Au
{f9613a2a-495d-431f-92d3-4cb658f469e4} 6 -