I have only been using the powdered black tourmaline in computer and modem USB and ethernet jacks which tend to get a bit warm from the heat hose units generate, so perhaps that is why I am finding it somewhat helpful there. I have not found tourmaline helpful around audio RCA jacks or audio interconnects. I do use Cardas caps for open RCA jacks. Also black tourmaline was somewhat helpful on my AC connectors which may get a little warm. I also have some tourmaline inside my tubed DAC placed near the rectifier tube which presumably is hot enough to generate a decent benefit which I heard. I haven't heard anything special from placing them near my integrated amp's exposed tubes yet, but I will try that again sometime. Definitely got a small advantage inside my small BPT conditioner which is used for computer audio devices with SMPS.
A very pleasant surprise was the increase in cleanliness overall from a red fire agate stone near my fuse box. Odd thing is that tourmaline seems to be good around the fuses themselves but definitely not on the other side of the same box which is accessible from my cabinet and is encased in plastic and inside a steel box. On that other side the agate seems to be very helpful.
Geoff, at some point I would like to try out your pebbles for RCAs.
