Try a link below as a reference.

http://www.kabusa.com/pregain.htm

If you are looing for a outboard phonopre that will offer very similar gain stage to your Adcom, then look for one that offers around 40-41dB.
But with your cartridge, idea load shown on the calculator is 34dB of gain. Output of 6.5mV, you will never have to worry about not having enough gain.

Which Bellari are you looking at? Bellari V129 seems to be popular, but V29(Not V129) is absolutely the worst audio gear on the market.