Grimace,
Some phono stages aren't designed to provide sufficient gain for a moving coil (MC) cartridge (or they may be able provide sufficient gain, but it pushes the phono stage to the uppper end of its limits). A step-up transformer (SUT) can help in this situation.
For example, I used to own a Wright WPP-100c phono stage and a Shelter 501 mk II cartridge (MC). While technically I could get enough gain from the phono stage alone, the Wright isn't designed to work with low-output MC cartridges, and IMHO it didn't sound as good as when I used a step-up transformer along with the Wright WPP-100c phono stage. If I was using a high-output MC cartridge or a MM cartridge, a SUT may not be necessary.
Now I use an Ayre P-5xe with a Denon 103R cartridge. The Ayre phono stage is designed to work with low-output MC cartridges, so a SUT is not necessary.
This is an oversimplification, but you'll get the picture.
Some phono stages aren't designed to provide sufficient gain for a moving coil (MC) cartridge (or they may be able provide sufficient gain, but it pushes the phono stage to the uppper end of its limits). A step-up transformer (SUT) can help in this situation.
For example, I used to own a Wright WPP-100c phono stage and a Shelter 501 mk II cartridge (MC). While technically I could get enough gain from the phono stage alone, the Wright isn't designed to work with low-output MC cartridges, and IMHO it didn't sound as good as when I used a step-up transformer along with the Wright WPP-100c phono stage. If I was using a high-output MC cartridge or a MM cartridge, a SUT may not be necessary.
Now I use an Ayre P-5xe with a Denon 103R cartridge. The Ayre phono stage is designed to work with low-output MC cartridges, so a SUT is not necessary.
This is an oversimplification, but you'll get the picture.