I talked to the Lyra guys who were very helpful. I was all wrong with what I was doing.
They clarified their instructions. The load that you use with the Delos should be the same regardless of whether you use a SUT or a MC phono preamp - that is, > 90 Ohms. The note about SUTs in the instructions does NOT refer to loading. It refers to the kind of SUT that you use. The SUT should be one that is designed for cartridges with an internal impedance from 5 - 15 ohms. The Delos is about 8.
The 10x SUT that I was using was designed for 20 - 40 ohms cartridges, not low impedance cartridges. I don't know how low and high impedance SUTs differ, but apparently they do. The other SUT is designed for low impedance cartridges but has 16x and 32x taps. Without loading these down significantly, my MM input was overloading - too much gain.
So bottom line is that the specified load for the Delos is > 91 ohms, regardless of what sort of step up method that you choose. If you choose a SUT make sure that you don't overload the MM input.