**** connectors will make a good splice if you crimp them right. I would strip the plastic off of the **** connector, crimp and then solder, but you don't have to solder. You need to wrap the splice with something more than electrical tape IMO - plastic electrical tape isn't tough enough for a splice in the middle of a cord. I'd suggest the rubber tape electricians use - wrap each spliced wire, then wrap each wire with plastic tape (just to keep it from unraveling). Wrap the whole knot with more rubber tape, then plastic electricians tape or heat shrink, depending on how good you want the splice to look.