Can I use a step up transformer?

Hello.
K&K audio sales Lundahl transformers.
They have a kit that can be upgraded to their silver transformers. 
I have one and a friend has one.
I don't think you will find anything that sounds better at any price. 
But the cost is just over 1500.00
This is the best audio purchase around. 

Dear Nandric,
25 is enough :-)
or?

Dear Thuchan, How could I know; I own  only two?

You can certainly try a step-up but in my experience they color the sound too much and lose the low end. I've had Sony, Denon (2 kinds, they where the best IMHO), Dynavector, & Fidelity Research, they were great investments, I sold them all for more than I paid so I've not heard everything but I just find a well designed solid state phono preamp much more transparent. I use a Monolithic PS-1 with the PA-1 upgrade power supply, $1100 new with my Dynavector 17D Karat and Grace Ruby FE9+. I've heard better RIAA preamps but only over $4k. I'd love to try a tube preamp but too much money for me right now.

Humand,
matching MCs with the appropriate SUT is not an easy job. If you are using SUTs and they do color the sound, are loosing the low or high end, you definitely have a mismatch. And the result will be like you described.

Working with many phono stages and SUTs I found quite some limitations with 'active' phono stages that 'passive' SUTs overcome.