Speaker buzz with SS amplifier, input disconnected

If a buzz/hum is present from my loudspeakers with solid state Monoblock inputs disconnected, what are the likely possibilities accounting for the buzz. Do toroidal transformers ever transmit transformer noise to the loudspeakers?
I thought ground loops were more or less eliminated with amplifier inputs disconnected. Buzz/hum is present in both loudspeakers(with inputs disconnected), more pronounced in one. Thank you for your suggestions!

Amplifier. Gamut M250
Speaker. KEF Blade