Never lift grounds on power amplifiers. you don't want that to go live with the currents that can easily kill you. If however your house is correctly earthed the breaker should go before there is any damage done to the equipment or more importantly you. Unless as said above manufacturer has a ground lift capacity on the board " no "always leave grund in place. if you have a ground loop "buzzing" noise lift the earth on the pre amp as interconnects can more than likely handle that current going back to earth. But as said check connections are tight and that balanced connectors are wired the right way in phase etc. Pull the power amplifier as far away from the sensitive circuits in the preamplifier as some are oversensitive and away from central heating circuits , strip lighting. There are many noise sources that cause these issues. Often here is no need to jump to lifting mains earth on audio gear.
To Float or not to Float...
I have a DeHavilland preamp which has a switch allowing one to "float" the ground. I've always used it in the "float" position, however recently, perhaps due to some connectivity issues with my interconnects, there is a small buzz emanating from my speakers with the switch in this position. The buzz disappears when I flip the preamp switch to the "ground" position. Irrespective of the buzzing, is there any sonic advantage (or disadvantage) to "floating" the preamp ground in this situation??
Thanks for your informed opinions...
Thanks for your informed opinions...