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
Buzz and hum are two very different things. Transformer noise is hum and is emitted at the amp itself.

Since it's both channels try some easy trouble shooting for hum....
1. use a different AC line with no other sources on it.
2. only have one amp powered up and see what you get. Remove the 2nd amp from the system.

Most importantly, are you using a vertical or horizontal biamp? I'm assuming each speaker has it's own amp.
Most amps will make some kind of noise when there inputs are disconnected. When you reconnect the inputs is the noise gone? If gone there is nothing to worry about

Like Arh is asking above, is this a really bad hum/noise or is this just the tiny hum you might get from a floating input?

When 60 Hz hum becomes really bad, it can create a buzzing hum. The 60 Hz wave is so strong that it clips off at the peaks and creates many new frequencies that are higher order harmonics of 60 (120, 240, 480, 960 Hz, etc.).

If this is a pretty loud hum, then it sounds like you have either had a big electrolytic cap in the power supply going bad, or there is a short in the amp that is so bad it is bleeding the power supply down. If it is an internal short, then it will smell bad and be overheating. If it is just an electrolytic filter cap, it might slightly smell acidic, but won't be overheating that bad.

Anyway, sounds like she needs an overhaul.
The noise through my Blades is unchanged with inputs connected or disconnected to the Gamut monoblocks. It is more of a buzz than hum, and is audible about 3 ft from loudspeakers. Speakers are not biamped and noise persists when plugged into power conditioner, DC Blocker or
cheater plug used. Can an amplifier itself transmit buzz into a loudspeaker?
Gamut claims it must be dirty AC, but I don't believe this to be the case?
When I use my tube amplifier, no hum or buzz evident.
Thanks again to to those responding.

Buy a pair of shorting plugs for the inputs of the Gamut monoblocks. If you still have the buzzing sound heard though the speakers try plugging the amps directly to the wall outlet and then check again for buzz.

If the buzz still exists.
Which Gamut monoblocks do you have? Are the amps enclosed in the same chassis unit or entirely separate units? If the amps are housed in the same chassis unit the problem could be the monoblocks unit.

It is possible some electrical appliance or device in your home could be causing the problem. It could even be a problem somewhere in the electrical wiring like a loose connection that is slightly arcing. Only way to rule out the mains power is to hire someone with a background in Power Quality and connect a scope to the mains of your home.
This sounds like an internal layout problem to me. It is true however that with an open input (nothing connected) that there will be a greater amount of noise present. But that should be gone with your preamp connected.

Now one exception may be that your interconnect cable is responsible for some of the buzz. So it is a good idea to try a different cable before blaming the amp!
Thanks Attmasphere/RK
I've tried a couple of interconnects without change. I believe you are right about an internal layout problem. Both monoblocks buzz through the loudspeakers, one louder than the other, inputs either connected or not.
Would you kindly expound on the type of layout problem which might result in this speaker buzz. Can a noisy toroid transmit buzz to loudspeakers etc
I know most talk of noisy transformers in the chassis without transmission to loudspeakers.
Many thanks for your response!
Hi Brian- I had a similar issue with BAT monos a while ago. I would get a hum with the speakers connected and no input connected to the amp. Your amps were designed to run with XLR input and the amp will hum if there is no device plugged into the XLR inputs, so hopefully you have a preamp that has XLR outputs. IN the manual of your amplifiers, it states "In case you have a preamplifier with only RCA outputs, you can use the RCA input. Remember to plug in the XLR Terminator plug, when you use the RCA input. It connects the negative input to ground, making sure that the input is not “floating” with the risk of noise or oscilliation comming in to the amplifier circuits." So - connect the inputs of the amps with an XLR cable to the outputs of a balanced preamp and the noise should disappear OR use the RCA inputs to connect to the preamp and use the XLR Terminator plug as described and the noise should also disappear. I hope this helps.
The buzz is constant with balanced inputs connected or disconnected. I am using balanced cables between my VAC preamp and the Gamuts.
Thanks!......still buzzes, both channels but more on one side.

Did these amps have this problem from day one, or is this recent?

Do you have any other equipment near the amps that is on?

Do you have florescent lighting or light dimmers?

If you swap the physical position of the left and right amps, does the greater hum stay with the amp?

If you move one of the amps and speaker to another room, is the problem still there?

I'm trying to figure out if you might have electromagnetic pickup (radiated pickup). You can tell if it is radiated because when you move the amp around, the pickup will be greater or less.

Dimmers and florescent lights transmit higher frequencies that sound like buzz.

Power conditioning doesn't get rid of radiated pickup.

Possibly both amps are having electrolytic cap breakdown, but that normally happens one at a time on older amps.
Thanks for your thorough inquiries, Tom32.
The amps have had this problem from day one, for approx 2 months but is inaudible over the music...only between tracks etc.
Actually my equipment rack is removed from the amps and loudspeakers, with a 5 meter balanced IC between my VAC pre and Gamut M250 monos.
No fluorescent lighting or dimmers.
Yes, the larger hum stays with the amp and there is apparently no change with change of room (I used a monitor speaker in room #2 as the Blades are too big to move!
I think I will send them back to a Gamut for non warranty investigation/repair.....thank you to all respondents !

What I meant about moving it to another room was to see if a different AC branch of power or if a different electromagnetic environment caused a change. You should check everything before going through the hassle and cost of sending it back. Also the repair dude is going to be pretty puzzled if he gets them on the bench and can't find a hum.

But is sure does sound like a power supply hum to me.
Would you kindly expound on the type of layout problem which might result in this speaker buzz. Can a noisy toroid transmit buzz to loudspeakers etc

Generally a noisy power transformer will not cause noise in the audio path as well. But there can be AC line problems that can cause both noise in the amp and mechanical noise as well. Sometimes it can be confusing to sort them out.

The fact that one channel is noisier than the other is a clue. Without knowing any more about the amp I can't say more about layout, but that is what it suggests to me. IMO the amp should get checked out.