For what it's worth, here is the product detail (PDF format) for the KW-500. Page 10 has the specs for the phono input. No gain mentioned, but it does have the 'Overload Margin'. Not sure what that is...
http://www.musicalfidelity.com/downloads/archived-manuals/English/kW500.pdf
-gh0st
http://www.musicalfidelity.com/downloads/archived-manuals/English/kW500.pdf
-gh0st