How many opamps does it take to find the peak amplitude of a signal?
I think you can do all of this with just two op-amps (although someone will probably correct me).



The first stage is the peak detector and decay. The op-amp is wired to emulate a perfect diode. We take the feedback signal from after the diode so that the op-amp drives hard enough to overcome the voltage drop of the diode. Being a peak detector, it doesn't really eed a rectified signal. The capacitor holds the peak value, while the resistor decays it. You can make the decay slower by choosing a larger capacitor and resistor. And vice versa.

The second stage is simply 15x gain. It has low output impedance.