Mil spec hardening was 80 dB since the starfish prime tests of 1962. If we learned anything from the USS Fitzgerald incident, summer 2018, it's that stronger pulses have been developed. The practical limit is over 300 dB, and my own hardening of my shtf HAM radio approaches 400 dB worth of hardening. Farraday cage inside copper Farraday cage inside aluminum Farraday cage inside galvanized Farraday cage. Overdoing it beats underdoing it.
Strategically, there should be a second EMP anywhere from 2-6 weeks after the initial pulse, to take out the backups. So now you need 2 sets of EMP preps.
After the EMP, barter will replace commerce, but the one thing you won't be able to barter for will be un-fried electronics. They'll be worth more than food and gold and ammo and smokes and booze and water filters combined.
Jakob the Liar shows the need for communication in times of shtf.
You may want to protect Kindles, hand crank generators, walkie-talkies, automotive computers to try to resurrect computer-controlled cars, or other electronics, and if so, that's your prerogative, but of the 4 thingsx on my list, the only one I revealed here is my HAM radio.