GETTING MY TRANSFORMER 277V TO 240 V TO WORK

I've introduced "Yamaha receiver RX 681" and polkaudio subwoofer from United states which operate on 120v 60hz but in India I've 230v and 50hz.I have two European appliances and I can not use it in the US. So I ordered this voltage converter from this seller. Just like The outline, they work as expected. From:Omega Morgan’s workforce of venture p