A suggestion. A step-up transformer for a moving coil cartridge is a ridiculously easy way to get into DIY.
The finished boxes that you see often contain little to nothing more than a raw step-up transformer or two (Sowter (UK) makes a good one, Lundahl (Sweden) makes many good ones, and there are others that I haven’t tried) which cost maybe 200 - 300 GBP. Add some inexpensive connectors (XLR from Neutrix, RCA from Switchcraft) and a box, and mount the parts in the box, and you have something which competes with the big boys. You don’t need to switch them - it’s better if you don’t - just follow the manufacturer’s recommendations for hook-up and you’re done.
Most people think, OMG, it’s magic, the pros know all this stuff that I don’t, so I can’t do anything. This is a mistake. The pros do know lots of things, and one of them is, that manufacturers give detailed instructions on the use of their equipment. They are often called ’Application Notes’.
A pro would never think of using something like a transformer without looking at an application note, or at least an explanatory drawing (called a ’schematic’). Why not call up Sowter, explain that you want to build a SUT for a MC, and ask for their advice? I found them very helpful when I did that 10 years ago.
What have you got to lose? Are they going to take away your corner office?