best way to convert 230 V Luxman LV-103 to 120volt

I just picked up this cool little hybrid unit but it came from Asia and has a basic looking external 500W 200 to 120 volt transformer.

Any suggestions as to whether to leave it as is or swap out the internal transformer much appreciated.

btw - tremendous sonic clarity compared to by old Bryston 3B on accoustic/vocal music but she does struggle with my AC/DC... bass is clear but not very prominent.
I use a goldsource step up step down 2000 watt transformer to do the reverse - USA voltage in Europe. It's made in China, on amazon and has worked well. It also has user changeable fuses which I like. I cannot hear coloration from the transformer on my system. It's very heavy but not large and allows you to use your own power cords. Btw I wish ps audio or others would consider making a step up step down option on thier conditioners, I think there's a market for it.
Thanks for that.
How did you calculate that you needed a 2000 watt transformer?
what is your opinion of a 500 watt transformer for the job?