Soulnote relays were made by further adapting the proposed relay as an alternative to mercury relays, whose use was banned for environmental reasons. Even when compared to the bare wire, the sound quality was so good that there was almost no difference. 

This custom glass tube sealed relay is very expensive, more than 10 times the usual price. The P-3 preamplifier has a total of 96 relay switchable volumes, an input selector switch that switches to GND, and an output mute switch. All Soulnote D-3s have adopted this relay as well.