.... Iron Maiden (Rock In Rio 1895).
Wow you are old... I guess so is Maiden... I did see Deep Purple in 1986 from the 9th row, and during the bass and organ solo, my insides hurt (and I will leave out the manly details of where you could really fee the music ripping thru you)
Old? Ancient, I would say

I was more than fortunate to be there. My family was always going to the US and Europe and suporting a 15/16 year old teenager to go to those concerts.
Great times.
HA, and I thought I am old

....BUT I also saw my 1st concert in 1974 at age 5

.....not nearly as loud as Deep Purple I guess HAHA.....it was ABBA

Don´t forget your earplugs dude!

Go line-in with bbox and all will be good.
Rec level 12-15/30 should be a good one to start the show with as you have low-sens cardioids.
If you can´t get good levels even at level 30/30, change to mic-in...I did the same with my dpa4061 mics taping URIAH HEEP pretty close to the stacks(about 20m in front ofthe right stack) at an outdoor show.