After reading this thread I also removed C4. Quite an improvement! Thanks Peter!
At this point I have no need to try the other mods of C5/L1. For me it's just fine like this.
I do agree with both Peter and Hans. Without any knowledge or the right soldering tools it's a bit tricky.
Use a small solder tip, a small bellow to suck up the tin, and a magnifying glass.
Despite having all this and working carefully I almost screwed it up when some soldering tin shorted with the other components.
Luckily I could remove that quickly.
It was a great relief to hear that the amp still worked and sounds much better than before!
