The PGA 2310/2311 is a digital pot with great sound. Texas is also easy to get samples from. Otherwise the circuit is a bit pricy if I remember it correctly.
Also check this site, there you will find more disscusions about HIFI and audio stuff: https://www.diyaudio.com/
Any one has did it and used PIC16F84 to make a digital volume control, I ahve seen the post samcheetah provided, I want PIC16F84 to control any of the ICs in this thread, not sanyo's only.