Mark, I have a 1:10 Wright SUT that I additionally add resistors via Y connectors, bringing the "stock" load of 100 to 40 ohms instead (to more closely match the DL103 impedance). I also use a 1:36 SUT built from Cinemag transformers (by a friend) that sounds excellent, to my ears anyway. It provides a load of 37.5 ohms without adding anything to it.
Whether you go with a 1:10 or a 1:36 you'll be way better off than with no step-up with the Denon.
Some people really like the Denon step up, you might want to do some research in vinyl asylum as well as here. It's cheap, it's plug and play, and people say it works well. I've never used it so I can't provide a first-hand account though.
Jim