What I've been doing is using a high gain on these AGC amplifiers - in the premise that for low volume sounds, the high gain will amplify the signals to suitable level, but for louder sounds the AGC kicks in and reduce it only care about frequencies below 160 Hz so gain bandwidth limit of op amps isn't really an issue, so I tried using a gain of 2 Meg. I noticed with the FET version, that it would work well, and then cut out momentarily, and repeat this- I wonder if this is something to do with the attack cutting out.