The D03K is a digital audio analog converter, which can transfer digital audio (optical / coaxial) to two channels analog audio and output (using directly on headphones is not recommended).
Digital Audio Analog Converter
Suitable for using with CD/DVD/Blue-ray player etc...Devices that feature coaxial or optical digital signal output.
When using WLAN headphones users can feel confused that the tansmitter of wireless headphones cannot connect with their TV which does not have a suitable connector. The common connectors of the transmitter is a 3.5mm analog input, whereas many digital TVs do not offer analog output connectors.
Based on the example set up we would need something to transform the signal. Fiio TAIShAN-D03K is the solution for you. The TV digital signal can input the WLAN headphones once transformed.