Your thoughts on a phono step-up transformer?

I recently bought a vintage high-quality turntable, which included a vintage "Reference" moving coil cartridge. My preamp (an MFA Magus) has a quality moving magnet input. As a step-up, I'm using an inline Ortofon STM-72. I'm not unhappy with the sound, but I have to think that there is more to be heard. A megabuck step-up is probably not in my future but I can see a $1-2K investment if it results in even better, more transparent sound. I trust this audio community, and your individual experiences, to recommend either a step-up (preferable) or a complete phono stage for my system.
I'm inclined to buy pre-owned but I have been known to stretch for the right component.

I welcome your input.