It would be nice to know which chipset version of the USB (laptop end) to RS232 female (HD621 end) cables work with Meridian.
I'm talking about single cable solution between laptop and HD621.
Amazon for example sells these cables with either PL2303 chipset or FTDI chipset. I have no idea what they mean, but sounds like the type of chipset matters.

G61RSL, DSP7200, DSP5200HC
Lumin D2
Akai GX-620, Teac A-3300SX, Nakamichi CR-4A, CR-2A
Oppo BDP-103
Sony PS-X600, Nagaoka MP-110, Denon DL-103R
NuPrime STA-9, Elac BS 63
PS Audio PP10