See if you can get a schematic of the Crown amps and I'll be able to tell you, as well as how to bypass it. Depending upon how they're put together it might not be difficult at all. Many pro amps have rear panel sockets go to the front panel with the attenuators and a 24dB filter would likely be here, off the main amp board. Connection to the main amp board would be via a ribbon or other cable, so once that's confirmed, a cable from the rear panel to the amp boards would bypass it.
“You are not special. You are not a beautiful and unique snowflake.” Chuck Palahniuk