I've found that getting into the wave-forms enables one to flatten the peaks one at a time; it's time-consuming but very controllable. I started recording with Lightly Polished D'Addario strings in order to minimize squeak, as recommended by John Williams, and I also found them very useful on my amplified guitars.
Lester Devoe Flamenco Negra
Lester Devoe Flamenco Blanca
Aparicio Flamenco Blanca with RMC pickup
Bartolex 7-string with RMC pickup
Giannini 7-string with Shadow pickup
Sal Pace 7-string archtop