But in my view,(need ur guidence)
Soundcard output impedence is low and our preamplifier input impedence is enough high. This impedence mismatching will cause the noise.. Am i right!!!.
I am using **broken link removed** for making PCB's. Many members of this web use Eagle(I think), But i like PCB123 becuse it is free and no restrictions.
The frequency response of a modern opamp like the TL072 with a voltage gain of only 7 is about 320kHz at low levels and 100kHz at high levels. An old 741 opamp has trouble above only 9kHz. An old LM358 or LM324 has trouble above only 6kHz.
The distortion is about only 0.003% up to 2kHz and less than 0.02% up to 20kHz. The old LM358 and LM324 have 3% crossover distortion with a gain of 1 and higher distortion at higher gain.