Just bought a brand new Marshall SV20H 20/5 head. The item came from Europe and has the two pronged Euro mains lead cable.  Amp power rating is 230V.

I used a regular US grounded three pronged cable into my power regulator at 125 volts.

I then went and bought the little plastic 2-pronged Euro to US converter and plugged that into my power regulator with no change.

The power output from the amp is very weak and fizzy/thin. on the high setting?

Is my 125 US Power rating and cable at fault?

How do I use this amp here in the US with a 125 regulated power supply?

Please advise....

Texas Guitars