I put two Soundspots on my Carruth Harp Guitar, one on the bridge plate under each bank of strings, wired in stereo. I use a Planet Waves Stereo 1/4" to two mono 1/4" cable that I hookup to my D-TAR Solstice, a two channel pre-amp, EQ, and DI that has phase switches on each channel with three bands of semi-parametric EQ.
The sound is spectacular and I've done a lot of experimenting with my Baggs amp trying to get it to feedback and had success defeating the feedback with the phase switches and EQ and still getting very nice sound. I can't wait to gig with this guitar now-it will have the presence I want for those subs.I play solo guitar in concert halls, churches, and house concerts, so I'm not too concerned with feedback issues-something that could rear it's head at high volumes, but I doubt very much whether I'll be hitting those volumes very often if ever.
I love the sound of the pickup on the subs, and in the studio will experiment recording using the pickup on the subs only and a mic on the guitar. Seems like a natural thing to do.
Here are links to the pickup and preamps. I am an official endorser.