Adjust panel meters on Step Up/ Down Toroidal Transformer unit. Model is SV-2000VA My mains here are 60 Hz 120 volts. The actual is about 123 Volts. This unit is made in China where it is 50HZ AC. My guess is the meters were a slightly low since mass produced and/or the circuit shifts some with frequency.

2000 VA 003 SAT AUDIO S22 3BW 8K