Do all toroidal transformers hum?

Thank you all for the responses, so you think most of the amps carry mediocre trannys?

Regards

Thank you Stanwal and Tbg, that was informative. The funny thing is that I had Denon POA 2400 (200W/channel) not a sign of hum, but the DK does have a faint hum. I guess I have to live with it as it's not audible 3 inches away from the amp. The Denon had a cheap 2-pront (no earth) power cable, do you think the grounding might be an issue? I had a B&K MC 101 Pre-amp with a IEC power cable and that had a hum too.

Thank You all for the great advices. Just want to make sure that the hum is not going to damage anything (I'm new to this stuff,so please pardon my ignorance). The DK does have covers on it's transformers.

Thanks Gbart, the fact that my B&K MC Pre-amp with external power supply also had a faint hum (again when I put my ear to the power supply), does that indicate a DC presence on the AC line?

Dstandard, where can I find your product catalog?

Nice work Gbart, unfortunately I absolutely have no knowledge of electrical circuits.

Amplifier hum problem SOLVED!!!. Gbart was kind enough to make me a simple DC blocker (with high quality Caps and resistors). I received it last night, I plugged the amp into it and VOILA NO MORE HUM. Not even a hint of it. I pressed my ear against the amp. to hear the faintest hum, but nothing, absolute SILENCE. You won't believe how much the DC blocker from Gbart costed... $72. Yes it's just Seventy Two dollats.

THANKS GBART

Well Gbart, I told I was a novice :-))