I was thinking that too John. When I went searching for some info on roughly what year digital volume controls became more popular than analogue (prone to crackles,)I found this interesting statement in a short article discussing the pros and cons of both.
"
A digital volume control has its own problems. Each 6dB reduction in volume from the maximum setting throws away one bit of resolution. A low volume setting (say, 30dB of attenuation) is equivalent to discarding five bits. If you had true 20-bit resolution in your D/A converter, you'd be listening to 15-bit audio instead of 20-bit. The lower the volume setting, the greater the loss in resolution. "
Anyone with better knowledge care to comment if this is still current and how relevant it is? Here is the link for reference purposes.
Volume Controls 
