@rmcfee SUTs require proper care and feeding if you want the best out of them.
Transformers transform impedance. So the output impedance is a function of the turns ratio and the source impedance (the cartridge and cables).
If the SUT is insufficiently loaded (load value too high) it will overshoot (ring), which is saying it will make distortion and be bright. If the load is too much (too low an impedance) the transformer will roll off highs. There is an exact value that is called 'critical damping'.
The cartridge itself doesn't care about the loading until the load is very close to the impedance of the cartridge. So your main concern is making sure the transformer is properly loaded (critically damped) so it will sound right. The correct value (which may be a simple resistance or might be a resistance and capacitance in series) varies with the cartridge and to a smaller extent, the tonearm cable.
This is why I prefer a phono section that has enough gain so I don't have to use an SUT; loading SUTs correctly is tricky and beyond the abilities of most audiophiles. I posted the procedure on a different thread recently.
(To take some of the guess work out of this Jensen Transformers has a pdf file that lists all the cartridges they've encountered for use with their SUTs. Unless your phono section uses a Jensen (which would be a good move as Jensens are some of the best available) that pdf doesn't apply to your situation.)
If you don't use the procedure the result is very much like building a loudspeaker from scratch without knowing anything about speaker design. It will certainly play, but sounding right (being neutral) will be up to chance.