Step up transformers, good, bad or maybe?

[The Grand Wazoo]

Thanks again for more info. Do you have to decide on the actual cartridge to be used so that the SUT works in harmony (no pun ) with one another? what happens at a later date if you change to a different make of cartridge? Looks like I will have to finalise on cartridge to be used first???

I'm getting there, I think

Ron

Not really, there are two main variables - step up ratio & loading. The ratio is the thing that could possibly limit future choice of cartridge if you decide to go for something with an incredibly low output, but it's usually nothing a twist of the volume knob won't cure.
The loading is usually easy to vary to very fine degrees by adding a resistor of an appropriate value - some SUT's have a bit of choice here as standard.