The power transformers on my Welborne DRD 300B monoblocks would audibly "buzz" when I plugged the amps into 2.4kVA Topaz Ultra-Isolator trannis wired in balanced config. It was actually so scary that I would have to unplug them after only 5 seconds.
After weeks of frustration, I shipped them back to Welborne. Embarrassingly, the problem was so simple I could have fixed it myself withing two minutes if I had just calmed down and thought it through - the star-grounding just needed to tightened slightly.
Since then, quiet as can be. No problems with the rest of my components, either.
Just remember to turn off the power at the transformer when not in use because the component's own power switch will only turn of off half of the 120V in 60V-0V-60V configuration.
After weeks of frustration, I shipped them back to Welborne. Embarrassingly, the problem was so simple I could have fixed it myself withing two minutes if I had just calmed down and thought it through - the star-grounding just needed to tightened slightly.
Since then, quiet as can be. No problems with the rest of my components, either.
Just remember to turn off the power at the transformer when not in use because the component's own power switch will only turn of off half of the 120V in 60V-0V-60V configuration.