Audio Noise from my step up/down transformer

I just bought a 220V Pathos TT integrated amplifier and it came with a PowerBright Step up & Step down Transformer for use here in the USA.
I am hearing noise coming through the speakers that I think is coming from the step up transformer.
When putting my ear next to the transformer there is a noticable low hum and when listening to the noise in the speakers it has the same pitch as the transformer but is several octaves higher.
The noise is present in the speakers whether the volume is up or down although the noise gets noticably louder when turning the volume all the way up

Any thoughts?

Thank you
DO you hear it the same with any source switched to on the integrated, for example phono (if present) versus aux or CD?

See if physically moving the transformer further or closer to the integrated causes a change in the noise level at a particular volume.

If so, relocating it further away from the integrated might help.

If moving it further away seems to help but you can't move it far enough away, consider options to add some additional magnetic shielding around the transformer for better isolation.
You probably have a power imbalance and you are using too small of a transformer for the task. This causes transformer core saturation on either the positive or the negative AC cycles... leading to harmonic distortion and a DC offset that induces noisy ground loops which are easily picked up on RCA interconnects.

Your amp uses something like 240 Watts when run at 220 volts suggesting it will need around 500 watts at 110... so I would use at least a 1000 watt transformer to be on the safe side.

P = I X E

P = power, watts, va
I = amps
E = voltage

P is the same on both sides of the xfmr.

I would agree more than likely the problem is caused by a ground loop.

I can only assume the step-up transformer is an autotransformer.
Could easily be checked with a continuity test.

Unplug the xfmr from the 120V power....

The neutral blade on the 120V plug will have a common continuity with the 240V neutral contact of the 240V receptacle.
At the 240V receptacle, there should not be any continuity between the safety ground contact, of the recept, and the neutral contact of the receptacle.

A temporary test using a ground cheater could be used on the 120V plug of the xfmr just to check for sure the problem is indeed a ground loop hum problem. (Only perform this test if the xfmr is an autotransformer.)
The hum from the transformer is mechanical and not necessarily translated directly to the quality of the AC to the amp. That mechanical hum could be a symptom of saturation caused by overloading or DC offset but some just do that in some places. In other words: Don't shoot the translator. At least, not before questioning the usual suspects.
Saturation also happens when voltage is too high. It is not only mechanical hum but also sinewave distortion.
Thanks Guys!

It turned out not to be the step up transformer. The noise came from some circut boards inside the amplifier itself. When I reported it to Pathos, they sent me new boards, and I put them in and the noise is gone!!