Just ran a blind test with Code 51 vs Horus pigtail adapters. People argue if they can or can't hear the difference between cables, so I wanted to find out if the same goes for adapters. The cable is typically 1.2m, pigtail adapters about 6" with a wire part being only 2.5"-3". Typically, I prefer pigtail adapters since they extend the cable instead of extending the plug, so it looks cleaner. In theory, shouldn't be a big contributing factor since this is a short piece of wire, but in practice turned out to be a different story.
Tested it with LPGT, playing the same track at the same volume, using U18t w/Code 51, and my wife switching between Code 51 and Horus pigtail adapters while I'm not looking. Got it right every single time, with Code 51 adapter giving a touch more body to the mids while Horus making it a touch brighter. Very subtle difference, but with trained ears you can pick it up. Again, all goes along with the conclusion of my Code 51
review, some people go for a perfection at a premium cost, especially when dealing with 4.4mm and 2.5mm flagship DAPs.
The picture below also shows the difference between thinner 26AWG Horus wires (the slightly longer pigtail adapter at the bottom) vs thicker 24AWG Code 51 wires (the one above it). Still, both adapters feel supple. And, Code 51 pigtail adapter also has matching titanium housing plugs.