Balanced usually uses xlr connectors. Unbalanced, or SE (single ended) usuallt uses RCA. Don’t get hung up on it, just use rca to rca and you should be fine.
Analog system, upgrade preamp
purchase most of my equipment during 79-82 timeframe while serving overseas. Amp is SAE 2600. Purchased Carver 4000 (used) to replace Carver CT-7. Not happy with it. Looking at Classe CP 50 or Conrad Johnson PV 10A update to the preamp. have searched and do not understand how the "Balanced and Unbalanced" connection will fit into my system which all jacks are RCA. Do now want to start a change and end up changing more than intended. trying to bridge a nearly 40-year gap in my equipment however, the knowledge gap may be impossible. Any advice on either of these two pieces and how they would fit into a completely ancient analog system would be greatly appreciated.