JL Audio F110 Loud pop when pc unplugged ?

I like to thank you all for your responses.

Whenever I planned to do some work with the subs, I turn off the front ON/OFF switch overnight allowing the caps to discharge.

I had to unplug the power cords a few time because of re-postion and pc replacement.

An IEC to each sub. Balanced feed and no slave. The subs are powered down before I unplug the pc and volume setting does not make any difference.

My next test is to allow the discharge time for 40-50 hours before unplugging, perhaps overnight is not long enough.
I will post the results.

You might want to call them up or email them, overnight should be plenty of time.

mine do it to FWIW. i generally never unplug, unless leaving town.

The reason is likely with the way your power cord plug connection is made/broken to your electrical outlet-and has nothing to do with your unit. It seems your plug's ground may not be making a solid connection or your receptacle is faulty. I would recommend checking and cleaning each with particular attention to the ground connection. By any chance had you disconnected or floated the ground? You may be able to test this idea by simply using a $10 or $15 polarity/ground tester to start, at your receptacle.If things are ok try using any grounded extension cord and retest the receptacle on the extension cord. If all is ok you plug into the extension , listen a while and power down and wait 5 minutes. Capacitors, after having been warmed and played, start to discharge immediately upon turn off of incoming current with their energy dissipating mostly in the 30 seconds after turn off. I'm assuming your amp is connected to speakers of course. If there is no pop you may have confirmed the problem is related to the plug/receptacle interface. If so I would upgrade your power plugs; usually an easy worthwhile improvement for any power cord. If not lets discuss more. Good luck. Pete

Plate amps had a malfunction and after replacement the problem has disappeared.
I am very lucky because there is a JL service depot is in my area and replacement covered under warranty.
I did the work myself because if the high gloss finish should get damaged I am the one to be blamed.
Thank you.