Just some additional comments. I have used the BL-Ag in the past, which is somewhat similar to BL-1, but uses 2 x 23awg solid-core silver. I have done the floating drain wire scenario, but I could never get the cable to sound open enough. I ended up just soldering both the 2 x 23awg solid-core conductors directly to the signal pin of the RCA and soldered the drain wire to ground on both sides of the cable. This really opened up the sound (a single 23awg conductor just sounded too closed in).
Since the BL-1 uses 2 x 20awg stranded conductors, you may not have this problem, but I’ve always found that larger awg will allow more punch/power in the bass and overall better open sound (essentialy, less resistance in the entire cable, and it’s easier and faster for the preamp/source to charge the cable when pushing waveforms). You could experiment with soldering both 20awg conductors to signal pin and soldering drain wire to ground on both sides of interconnect.
On my interconnects nowadays, I always use 2x20awg solid-core for signal conductors (making a 17awg interconnect). This has proved to be the best solution so far.