Been there, done that when I worked in audio duplication (spoken books on cassette and CD... so that dates me). We had to have a reference system to test that randomly selected product was of sufficient quality. The system had expensive components and interconnects. For a laugh we hooked up 4 or 5 different speaker cables (twin core cable found left over by a sparky > couple of quid QED cable > all the way up to the reference stuff which was £*** per metre) and did random blind tests... not one person could even remotely identify the most expensive but the 'free' twin core didn't disgrace itself. A bit embarrassing for one of the lads who had just shelled out a big chunk of cash for his latest speaker cable!