S/N ratio Balanced input vs. Unbalanced input

Are you sure other sources into the amp don’t give the hiss?

@o_holter Ya, I tried my old Sony CD player which connect to integrated amplifier via RCA, I did not notice any hiss near tweeter.  I will do fast "switching" from balanced input (Ares II DAC) and RCA input (Sony CD player) to test the hiss noise.

adding "Cable Clamp Clip RFI EMI EMC Noise Filters “ 

@westcoastaudiophile my audio equipment are connected to a good power conditioner of Novaris brand.  I would think EMI issue shall not be the case, wouldn't it ?

@auronthas The reason your amp is noisier with the balanced input is that the amp itself has a single-ended input; its not internally balanced. So the balanced input goes thru a separate circuit which adds noise.

IMO/IME this is a sloppy way of doing things since the balanced operation is more of an afterthought whereas again IMO it should be the star of the show.

Normally if the internal circuitry were balanced-differential, the single-ended input would be noisier as there would be less noise cancellation.

This also explains why there is less noise when the balanced DAC is connected; the opamp that does the balanced to single-ended conversion is able to pick up noise with no input load.

@atmasphere What you said make sense. I will leave it if this not a defect, just not perfect.  Thanks