I will power it with more than 12V, e.g. the 19V from an old notebook power supply
Exactly what I was thinking myself! A notebook switching supply will have plenty of juice and then some, which I was thinking of directing to a 9V regulator to power 9V modules as well as a couple of outputs on a front panel for use with guitar pedals.
I have a couple of concerns, however, about switching supplies’ noise and the DC coupling needed for the single supply. Hopefully the RC filter and the hefty 2200μF capacitor at the output will take care of these, but do let us know how it works out for you.