Do step up transformers degrade sound?

I would first call the manufacturer. Having lived in London and New York and taken components in both directions, I have learned that they can often be changed quickly and easily for little expense. That would certainly be better than using a transformer.

Cw is correct. I had DAC converted by the factory for $50.

A step up transformer may not be necessary. The voltage at your typical household wall outlet is of course 120VAC, but there are two 120V "phases" incoming at the breakerbox or fusebox. Household appliances such as electric stoves, electric clothes dryers, water heaters and large air conditioners derive their power souces across both phases of 120V for a total line voltage of 240V, which is sometimes called "220" as you say above.
You can wire some special AC outlets for this higher voltage yourself (if you know how to do electrical work) or have an electrician install a dedicated "220" line for you. A different shaped AC plug is normally used for this purpose, in order to avoid accidents plugging the wrong component into the higher voltage - the outlet prongs are horizontal vs. the typical vertical 120V outlet prongs.
Actually, balanced 240V power is preferred to typical unbalanced 120V for any component capable of accepting this voltage option. Balanced yields quieter operation & halves the current demand.

Bob is TOTALLY on to it. 110% agree, the result of balanced power may quite suprise you - it IS an upgrade!

And, to get back to Cbird1's original question: step-up transformers, like any device connected to (and I sometimes suspect, placed anywhere near) an audio system, will indeed *change* the sound. Whether you think it improves it, degrades it, or simply changes it, can be a matter of personal preference. Never be afraid to try things! You may like the results, you may not, but at least you'll gain insight into what works and what does not. Then you can start posting answers to questions like these as if you were some kind of an expert. Just like me! :-)

Mike Elliott
www.ariaaudio.com