[sdiy] Query about SSM2164

[Tom Wiltshire]

Just a quick question about the Analog Devices SSM2164;

In the datasheet (below) there's a schematic of a basic Quad VCA:

http://www.electricdruid.com/QuadVCA.jpg

Now, they say that the control constant for this chip is -33mV/dB. Am  
I right in thinking that this means that +5V control voltage gives  
-151dB of attenuation?

The reason I ask is that they also say that the chip has 120dB gain  
control range, from +20dB to -100dB, so the choice of a 0-5V control  
voltage here seems a bit odd. 3.3V gives you the maximum -100dB  
attenuation, so why go to 5V? Why did they not put a 51K resistor  
above the 100K pot?

Datasheet: http://www.analog.com/static/imported-files/data_sheets/ 
SSM2164.pdf

Thanks,
Tom