the triangles mean this is a harness connector, connecting two harnesses, male to female, and the circles will tell you what connector it is on the list I mentioned in the previous paragraph. The number in the triangle tells you which pin in the harness connector.
if a connector goes into something like a speaker, you’ll have the number right there on the wire on the speaker drawing. For a harness connection, there are only two connectors, so the triangles are as shown. The dotted lines between the triangles mean it is part of the same physical connector in the harness. So in the amp diagram the top row of triangles has a physical connector for all 6 wires… the R333/i155 connectors… then they are routed differently, and are not part of the same harness, but the pairs are part of different connectors, however each pair is still together for those respective connectors…. Each pair has a dotted line, so they will both be the same connector on that part of the harness. There may be other things in there, you’ll have to search for that link number to see what else is using it.
the zig-zag lines indicate that they are twisted pair wires. some kind of protection – but not an earth-type protection
