I'm new to Step Up Transformers

I did not try the lower of the gain settings on the MC channel because I assumed that it would be too low.  But I guess it's as easy as flicking a switch to see what happens.  

  I should have thought of that. Duhhh

@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.

Thanks so much Atmasphere. The Zestos has Jensens (I'm told) in the MC channels. That's great info about SUTs. 

As a person who 50 years ago did build a speaker without knowing anything about crossover design (not speaker design because I blindly followed information contained in a magazine article), I’d say Atmasphere has a point. But if you read the pdf available at Jensen, you see they recommend a rather complex network of R and C to get correct loading. Almost no one actually does that in implementing any of the dozens of different SUTs mentioned on this and the many other threads devoted to SUTs. So what do all those reports mean or how should they be interpreted? With more than a grain of salt, I think.

But if you read the pdf available at Jensen, you see they recommend a rather complex network of R and C to get correct loading. Almost no one actually does that

You are talking about a Nobel network to dampen any ringing in the transformer.

The Zesto Andros has the Nobel network included in their circuit, along with loading options designed specifically for that transformer/zobel. I know this because I installed an in field factory upgrade on a Zesto Andros a few years ago.

The slight complication here is that the Paua is a moving iron not a moving coil so the behaviour will not be at the same as LOMC's.

Soundsmith can advise on which transformers are appropriate.