I'm new to Step Up Transformers

In fact many people do not know that proper loading is usually done from a selector switch on the phonostage in which the switch run through a series of resistors. Someone looking to have there preamp get the proper load for their cartridge is a very simple thing. Just look up the spec on the cartridge and insert the proper resistor in the phono input stage of the preamp.

@lowtubes If we are talking about an SUT in the signal chain this is just about guaranteed to not work. But if you enjoy the sound that's fine.

I ran an LP mastering operation and recording studio so I have LPs I recorded. My perspective is thus a bit different; using LPs you recorded make a great reference for really knowing what is going on.

If you weren't referring to an SUT in the quote above, the loading resistor is really for the benefit of the phono section rather than the cartridge. When the cartridge plays it generates RFI (Radio Frequency Interference) which might be as high as 5MHz on account of the inductance of the cartridge being in parallel with the capacitance of the tonearm cable. Some preamps react poorly to that RFI so their designers added a switch to allow you different resistors which detune the resonance that causes the RFI. But if your phono section doesn't care about the RFI its plug and play. 

If you were talking about an SUT above, the capacitance of the tonearm cable and the cable between the SUT and preamp plays a role in the correct loading values (meaning its not something you can just 'look up'). Sometimes the correct load isn't just a resistor but a resistor and capacitor in series.

There is no better or worse here. It’s what works out in your system

@lowtubes Actually if you get the loading right you'll find there is 'better' and that the differences between your various SUTs is less than you thought.

The Zesto Andros has the Nobel network included in their circuit, along with loading options designed specifically for that transformer/zobel.

A Zobel network is often used to damp a transformer. But if you change the source impedance, the Zobel network won't be correct.

If you really want it right so the transformer editorializes least, the only way to really know is the procedure at the link I posted earlier.

@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.