Mogami 2534. Mogami makes good interconnect cable. It's marketed as microphone cable, and has four XLPE insulated, stranded bare copper conductors covered by a spiral-served bare copper shield.
Single Ended - Gold plated RCA. The connectors are branded 'Osonic', and are high quality screw type, 24k gold plated, non-magnetic, but not locking. I don't think locking RCA connectors are worth the expense. The day after I get locking sockets for my input tubes, come talk to me!
Balanced - Neutrik Gold plated XLR, solder type, p/n NC3FX-B (female), NC3MX-B (male). Well-engineered, elegant design.
For XLR balanced connectors, the two blue conductors are hot, the two white neutral, and the shield is connected to ground. The connector chassis is left floating. Waffling the cable into SE mode is a little tricky, and the cable ends up directional, but the results are worth the effort. See the diagram.
The importance of the interconnects depends on their length. If you have more than 4 m or so, then I would recommend you consider equipment with balanced inputs and outputs. Not only are the pro-audio XLR type connectors better than RCA, balanced circuitry is inherently better suited for long cable runs.