I am also experimenting.No inner core cloth is best.I run mine with nothing but the air in the teflon.IMO little is best for this application.I have had interesting results thus far.My home made cable is very,very transparent,But I'm still working on the shielding aspect of it.I can't get it to work as a phono cable yet.To much RFI issues.As a basic IC Line level I think I have it just about on target.