How is the resonance peak measured?
By sweeping the head via a flux loop.
Is it audible?
Could possibly have audible artifacts if the repro circuit isn't band limited.
Would one find the loading network in the SHRO?
Of course!
What about write-only heads...would they benefit from a loading network?
That's a record amplifier design matter. You're heading way off-topic here. (And I don't have time for it. Sorry!)
