Sorry for late reply! To use 120V -version in 230V, you would need a step up transformer because you need to convert the 110V AC voltage to 230 volts. You can use a single transformer for a pair of speakers. For a pair of 6010A speakers it should have a power rating of at least 140 VA. We don't have any recommendations for brand or model. There will be no sound quality loss.
Best Regards, Jani Oksanen Customer Support Team