If you wish to use your PC as a source without using a UPnP serverit must have an optical or co-ax digital output.  This can then be connected to one of the digital inputs of your Naim.The USB socket of your Naim network player can not be used to connect directly to a computer as your Naim will only recognize iPods and ‘Mass Storage Devices’ such as USB sticks. (Although supported Naim do not recommend the use of USB hard discs as they can be electrically quite noisy and can adversely affect the audio performance of the product.