Hi Peter, with the healthy 0.56mV output of the Benz I would set the SUT for 1:10, that will load it well and should provide the best sound.
Use for a good while to get the sound quality imprinted on your mind before you think of any changes.
If you use the 1:20 ratio you will be putting a big signal into the phono stage and losing some of the headroom.
Cheers,
Alan
I love Hendrix for so many reasons. He was so much more than just a blues guitarist - he played damn well any kind of guitar he wanted. In fact I'm not sure if he even played the guitar - he played music. - Stevie Ray Vaughan