I was tinkering with my jazz last night and was contemplating getting some push-pull pots to do switchable series/parallel wiring on the DiMarzio DP123 model Js i have in there. I wanted to see what the difference was first, so I quickly rewired it for parallel operation for each pickup and recorded a sound clip. The first clip (series mode) was actually recorded a few months ago, and I am not sure I changed strings since then, so the difference in string wear is a factor. Even then, the difference in top-end response is pretty clear. http://files.hags2k.com/pickup-comparison-model-j-series.mp3 http://files.hags2k.com/pickup-comparison-model-j-parallel.mp3 I think I'll be swapping the regular pots for push-pull pots in the near future. Both sounds are interesting - the series sound has proven to be quite good at getting a punchy sound in a loud mix, but the parallel sound seems to be very much in the realm of "standard j bass" tone. For comparison, here's a clip I recorded with the stock pickups - I actually think the model Js in parallel do a better "standard jazz bass" sound than the stock pickups! http://files.hags2k.com/PickupComparison-stock.mp3 Anyway, hopefully this is useful to anyone considering the series-parallel mod for their Model J-equipped basses.