I saw Def Leppard when they co-headlined with Whitesnake and remember thinking that I’d never heard anyone use as much gain as Phil Collen, and he seems to have that sustainer feedback thing permanently on. I’m a big Def Lep fan, they performed a great set, but Whitesnake blew them away, back when Reb Beach and Joel Hoekstra were on guitar, not sure who is in their current line-up.
In my opinion, Phil’s fast picking technique is slightly lacking to put it politely, and years of hiding behind gain, gain and more gain seems to have made his technique quite sloppy. I guess you get a bit bored of playing the same licks in the same songs for 40 years, but it kind of detracts a bit from the song and the melody. He never really went full on shred mode on the classic albums, and I remember being surprised by that fast run in the Let’s Get Rocked solo. The songs are classics though and he’s earned the right to play how he wants.
I bet if you turned Phil down a bit, you’d find that Vivian Campbell’s tone is much more appealing.