hi, i am having an issue replacing the existing effects loop circuit with a metro zero loss circuit. i figured with the buffer in the zeroloss circuit it would take some of the noisy issues you get with the existing one. however there is no change...it actually seems worse... i guess its due to where the loop circuit taps the signal. i tried tapping at the master volume as i do on 99% of the marshalls and others.. but it grounds the signal ..... does anyone have an idea where to tap the signal for proper operation of the zero loss effects loop? thanks !