Are old hi-fi systems worth anything?

Are vintage hi-fi systems still valuable in today's market? With the rise of digital audio and streaming services, do collectors still seek out these older systems for their unique sound quality or is it more of a nostalgia factor? Are there specific brands or models that hold more value than others? And if so, what factors contribute to their increased worth? Additionally, what maintenance or restoration work might be necessary to ensure these systems retain their value over time?