Indeed! However, some manufacturers do exacerbate the problem by design, e.g. Naim where the transformers are tightly bolted against the case resulting in a resonance effect. I reduced the noise of a NAP100 amp significantly by inserting a few rubber O-rings. Probably invalidated the warrant but what the heck!

Main system - Sources (Kodi-HTPC, Vero 4k, FireTV, Sat) into Trinnov Altitude 32 (8-16) (+Roon), Trinnov Amplitude 8 amp & Vivid Audio (Giya G3, V1.5) and REL Stentor III speakers. Others: F80 + Raspberry Pi and other Pi systems.