Mogami 2549 (Standard) vs 2534 (Quad) etc

Just based on the docs, the quad has better noise reduction.  Not likely to be an issue in most homes unless you have long runs or are near strong RFI sources, like a radio transmitter or machinery.

Having said this, I prefer the pure silver DH labs.  Brittle but I've gotten rid of everything else.

I have cables made with W2549 and others with W2534. Both pair have the same Neutrik connectors; both are 25 ft long.

Five years ago, when my HF hearing was better, I thought that sound through the ordinary mic cable (W2549) had SLIGHTLY more HF response. Maybe.

I'd use W2549 for most applications. If in an area with extreme RFI, the W2534 quad cable, which has better interference rejection, would be better. But for ordinary applications, even running a line-level audio cable near a power cord, there is no need for a quad cable.

The DH Labs BL-1 is a silver coated copper cable.

+1 on the 2549 wire, I buy it in 500ft rolls and make my own XLR cables and RCA cables in what ever lengths I need, I use Nakamichi RCA plugs NO556 from Nakamichiplugs.com and for XLR connections I use Neutrik NC3FXX female and NCEMXX male connectors from parts-express.com

Eric may have meant to say the ConneX Cable BL-Ag Interconnect Cable, which is pure silver and pretty good sounding, particularly for the price.