I remember having Belles 150 for a few days than taking it back to the dealer "AudioConnection". The 60hz buzz was so dominating that the chassis would ring. It was NO WAY to listen to any classical music or electronica or jazz. It was only good for heavy metal or rock'n'roll. It was used, but no more than 4 years old. I tried to tighten the transformer screws -- turned out to be OK, Tried using power conditioner which I trust -- Panamax-Max5000(wanna try that one? pretty efficient and cheap, but no help). They decided to fully refund me instead and offered me 30% discount towards shopping on refunded money. I admit they're THE BEST in high-end business!
Added few $$ more and got Bryston 3b-st... Brought home, connected and whew! Whatta change! Just like trading in Chevy Cobalt for BMW 5- series!
Never heard or used Belles Soloist, but Bryston as a brand sounds more solid and tough in general. Not trying to offer you exchange the amp, but just heads up. Belles 150
that I had seemed to be showing the symptoms of unstable amp mainly for the facts of poor design from the beginning. Having in mind that you have poor power, you should purchase equipment that is capable of working in tough conditions. I don't think that Vette is able to outrun Tahoe or RangeRover on beach send or you can't use Porsche 911 to pull your house trailer -- ye know what I mean!