Android - Can I use my Android phone as a USB speaker?

Even though I marked this as answered I feel I need to add that I've managed to do exactly what I wanted with SoundWire and the default internet sharing on my phone as follows:

1. Install and configure SoundWire on PC and phone.

2. Share phone's internet connection via USB.

3. Assuming you already had internet on your PC, you now have 2 network adapters. You need to make sure you are using your old adapter for internet access. As far as I could find to do this you need to change the metric of your default adapter to 1 so that it is the preferred adapter by Windows (Windows 7 in my case).

4. You can check the server IP by typing ipconfig in the command prompt.

5. Connect from the SoundWire app on your phone. You get a message that WiFi is disabled, but it still works fine.

I'm not sure if a USB option is possible but someone please correct me if I'm wrong! This uses the headphone jack so it isn't USB but it is still a wired connection. The following should work but may be a bit flaky. Plug a headset jack adapter to split the microphone and audio input into the headphone jack of your phone. Then wire a standard audio cable into the microphone jack of your phone from the audio output of your computer. Last, download an application that routes the microphone input to the speaker and turn that on. When you now play audio on your computer, it should be sounded from your phone.