Probably need a step down transformer that can handle a little bit of scoots to run a stereo. Read the rear panel where it specifies the Input Voltage. Usually near the power cord. It should also mention the current and / or power consumption nearby. What does it say?
Based on that ya can find a suitable transformer to meet the requirement. Transformers are normally specified in terms of VA,
or Volts x Amps. example: A step down Transformer rated for 300 VA could handle 115 V @ 2.6 Amps on the primary side, and would output
230 V @ 1.3 Amps on the secondary side. So if your Stereo wants to run on 230 V @ 1 A u'd be OK with a 300VA Transformer.
If it ran on 230V @ 2 Amps, you'd need a larger Transformer. If it ran on less than an amp you could use a smaller transformer, so on.
As far as the frequency goes it should be fine. Internally there is probably a step down transformer for the power supply circuits. The iron core of a 50 Hz transformer is optimised for 50 Hz. So if running it on 60 Hz, it may run a little warmer than it normally would on it's design frequency of 50 Hz.
I'm not even certain this applies to all modern day power transformer designs, YMMV.
There might even be a switch on the rear panel to switch from 230 to 115 V. Mine does. Have ya looked?
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