Yeah, you can just jumper it if you need to ground. In my setup w/ 96 db speakers, there is hardly a difference in background noise with either setting - you have to have your ear on the speaker to tell. BTW, can you post specifics / pictures about your speakers? Maybe create separate Cymbal friendly speaker posting.
Although I've built several Hagerman kits, I bought my Cymbals from another fan. I can take a look at how the boards are fitted. I didn't see any modification. Maybe a picture would help?