This might help. I found a driver for Windows called Virtual Audio Cable that creates a software loopback from your sound output to your sound input. It does the job, but it attenuates the audio level by 12dB. I sent a request to Eugene to look at this problem, no response yet.
The trial version barks the word "TRIAL" every few seconds, but at least it allows you to determine if it will work for you.
http://software.muzychenko.net/eng/vac.htm
Read the help file thoroughly to avoid common pitfalls. Such as, you should start your player or output stream first to set the parameters (bit depth, 1 or 2 channels, etc) then start the process that dumps audio into VAC.