Controlling computer audio

Morning Y'all - -

I'm trying to do something that it seems should be fairly simple, but even after looking through this forum and other sources in depth, I just can't quite find what I'm looking for.

Basically, I have a communications receiver with an RS-232 port, and I've written a fairly in depth application to control the receiver, at least everything that the manufacturer allows to be controlled. One thing that can't be controlled directly is the audio volume of the receiver. What I'd like to be able to do is to route the receiver's audio through the PC via the mic jack, and control the audio coming out of the PC's speaker volume under control of the application. The PC is an HP Touchsmart with Windows 7 and Realtek HD Audio Manager. My application is all written in VB6. It might be nice to be able to record the receiver's audio as well, but if I can simply control it's volume under control of the application, I'd be thrilled to tears.

Can anyone help me and perhaps get me started with some code snippets??

Tnx in advance. This forum has always been extremely helpful.

Chief Brad