À part un DIYer du forum qui te fait ça, je ne vois à priori rien qui existe déjà en "petit, pas cher et dispo dans le commerce".
“The type of cap is not as important as the value of the cap, for guitar. In an Amp, your cap type is much more important, as the signal is being passed through the cap all the time. In a guitar, you’re not hearing the cap itself, you’re hearing what the cap is impeding”. Lindy Fralin