there will be a 3" delay circuit to prevent the boom, and a slow turn on power supply.
i have a couple of ne5532 and another couple of tl072, wich i could use, but this all about is a tube preamplifier, and i dont know if it is correct to use opamp before, even if the power of the signal stays low..
however the input signal will come from digital source , from pc or mp3 player... it will not be pure analog (ie phono)
so i dont know ...... wait for relays or build it with opamp?