OK, thanks. I've found a couple of candidates here:
http://www.thomann.de/dk/cordial_cmk_422_zwillingskabel.htm
http://www.thomann.de/dk/sommer_cable_square_4core_mkii_highflex.htm
I have been thinking that the AWG ~24 wires are very thin and used individually in a banana plug would be rather vulnerable. Since then I also noticed BTG having this notice: "
It is not recommended that you purchase 4 strand wire for Banana plugs because they wire is so thin."
If I can find 8-stranded wire, I could consider pairing them 2 at a time for each banana, or perhaps use this thicker (~ AWG 20) microphone cable instead for a more secure connection:
http://www.thomann.de/dk/cordial_csf_450.htm
Gary, are your banana connections soldered or screw type? I've only come across the screw types for now, and see no cable relief built-in. Having kids in the house, that could be nice
Have you wondered about the strength of your single stranded wires? Perhaps they are ~AWG 20 and not 24s.
If I can find a good fit, I'll try and put a nice shoe lace around the cable as sleeve and some heat shrink to secure it and see how it looks. And post the results.