Punch up the line art
To bring back some of the intensity of the pencil art, I’ll be duplicating it above my Base Colour group. Although a Multiply layer could do the trick, I’ll have more flexibility with colour if I use Alpha channels. I copy my adjusted pencils, bring up the Channels palette, and paste into a new channel. I invert the pencils (Cmd+I) and click the RGB channel to exit the Alpha channel.