Adapting studio equipment (e.g. eq) circuits for stompbox use?

[iforgot]

Hey,

I'm curious about the possibility of adapting circuits designed for studio equipment for guitar pedal use.  I know that input and output stages will need to differ to accommodate the lower level of instrument signals, and their (typically) very high impedance.  But there are quite a few things that escape me. 

For instance, I'm not sure about (1) what becomes irrelevant once we know we will be dealing with unbalanced signal.  I'm also not sure about (2) what changes need to be made to make circuits compatible with 9v (up to 24v with chage pumps) linear DC power like stompboxes typically use, rather than +/- 15v-24v switching DC power like 51x modules use.

To make this more concrete, take, for instance, this Neumann W492 equalizer circuit from groupdiy: https://groupdiy.com/index.php?topic=28332.0

Suppose I am only interested in the 4th filter, the high shelf filter with variable transition frequency - last page of the pdf.  Besides the problem of making sure the output is an instrument level signal, two obvious questions jump out:

1) What parts of the circuit become irrelevant once we don't need the output signal to be balanced?

2) What changes need to be made to make the circuit compatible with a linear 18v DC power source? 
(The circuit is setup to feed the NE5532 opamps with switching (+/-) dc power.)

(In case that wasn't obvious, I am quite new to all this..  I'd be glad to get more general reading recommendations about this issue if anything comes to mind.)