Stompbox circuit design and simulation software

[Widows]

Howdy. Wondering if any of you can shed some light on a subject for me....

My friend and I build pedals together and we were talking tonight about how we'd love piece of software that would allow you to design a schematic and layout (as with most CAD programs) but with the added bonus of being able to plug your guitar into an audio interface on your PC to see how the circuit you've just designed would sound. Essentially a digital breadboard or Beavis Board that would allow you to design/mod your circuit and listen to it so you can get it exactly how you like it without having to buy a shit ton of components to test on a real world bread board.

Does such a thing exist, or would it be more a case of learning to program vst plugins?

Cheers

[Seljer]

Most (all?) SPICE programs are capable of opening a .wav file from the harddrive and using that as a voltage source. The drawback is however that it's very very very slow.