Nvidia’s audio-over-HDMI options are more limited than AMD’s. Most videocards based on new Nvidia GPUs (e.g., the GeForce 8000- and GT 200-series) support HDMI via an adapter and many have a S/PDIF ...

The Tube Delight USB sound card is a portable USB sound card that looks like a vacuum tube. It connects to your PC or notebook, allowing you to connect speakers, headphones, and a microphone to it.