Just read the page 3 of Krell FPB manual, available online at Krell website.
However, page 1, Krell Current Audio Signal Transmission
(CAST): A proprietary Krell circuit technology for connecting analog components, in which the audio waveform is transmitted between components in the current rather than voltage domain.
However, page 1, Krell Current Audio Signal Transmission
(CAST): A proprietary Krell circuit technology for connecting analog components, in which the audio waveform is transmitted between components in the current rather than voltage domain.