I don't fully understanding all you are saying, so please correct me if I'm wrong.
Vdd is 5v, and audio is guitar, or possibly line level, so all well under 5v.
By DC coupled, you mean direct, less the cap. What value is the norm for this AC coupling cap? Is a .01 disc cap acceptable for mic/line/guitar Z?
I don't really follow you on the biasing. Since the 4066 is just a switch, would I bias *only* to reduce clicks in the audio? If so, how do I do bias to 2.5v? Two resistors as a voltage divider to get 2.5v, on the IC side of the cap, and the audio input from the other side of the cap?
One circuit I saw uses 1meg to Vdd on the chip input, and then a 1 meg on the other side of the cap, at the input.
Thanks!