Naturally, Woojer Strap needs a 3.5 mm audio jack or a Bluetooth connection as its input. Headphones are usually connected via the Strap's audio output jack. However, when using PC USB headphones, you'll need to set up audio mirroring so that both devices work simultaneously. 

While audio mirroring through Windows audio settings is one solution, the following solution is based on a PC software called VoiceMeeter. VoiceMeeter is actually a virtual sound card, but has various audio manipulating options, including audio mirroring. 

Follow this steps to set audio mirroring on your Windows PC:

1. Connect (or pair via Bluetooth) your Strap.

2. Connect your USB headphones.

3. Download and install VoiceMeeter.
4. Restart your PC.
5. Open VoiceMeter.
6. Set Hardware Out A1 to Woojer Stereo, and Hardware Out A2 to your headphones.

7. Set your PC default playing device to VoiceMeeter Input.

From now on, when playing audio, you'll get the sound through both of the devices.