There is a Stereo Digital Volume Control made by Crystal (really Cirrus
Logic).  It is the CS3310.  It has:
        127dB (!) of range
                95.5dB of attenuation
                31.5dB of gain
                0.5dB steps.
        0.001% TDH
        3-wire 16-bit interface
        Operates from +/-5V.
        Outputs can drive a 600 ohm load.
        Input/output is only +/- 3.75V.

Don't know how pricey it is.  A spec sheet is available at:

        http://www.cirrus.com/prodtech/ov.crystal/cs3310.html

Hope it helps.

Michael

When the way of the Tao is forgotten, kindness and ethics must be taught.
Men must learn to pretend to be wise and good.  --  Lao Tzu