traderbam said:Hugo's schematic may work ok but bear in mind that the connection between -'ve input and the feedback node will tend to make the amp gain dependent on input impedance. I would think this would be undesireable.
Minh said:I'm quite happy with the amp's quality, power and stability. I've adjust the offset to 0mV, the noise did drop by a large margin. But if you put your ear right infront the speaker you can still hear hums (~60Hz). I'm guessing that it's the toroidal that inducing the noise into the low level input. Hence the idea for balance input.