LR57. I bought the FX2 because it was less money. I have a Rogue Sphinx integrated amp which 100 RMS. I am not sure that would qualify as a low current component. However, I am sure you are referring to CD players, tuners, DAC's turntables, or speed boxes as low current devices.
Thanks for the heads up about the BC power filters, I wish manufacturer would explain the application and use of these devices to buyers before they ship.
Are the BC power filters, those devices that are shaped like a cherry bomb, or a small version of FX2?? I will check their website