There are cassette decks like the Pyle I linked to upthread you can buy that will allow you to convert to digital formats but the inexpensive ones are likely to convert to mp3, which is lossy. As @DPRK linked, using your computer and Audacity allows you to clean up the wow/flutter inherent in cassettes, and remove some noise. It’s a bit more work, but the end result is better; you can also save in lossless formats that sound much better to boot.
Very good advice in the thread; I’d like to add a few thoughts.
For a simple and cheap system, without bothering about really high quality, you might consider a simple all-in-one system from the likes of Yamaha, Pioneer, Sony or others. Look for Micro Hi-Fi System, e.g. 10 Best Micro Hi-Fi Systems | Experience Outstanding Music Clarity. These are amazing value for money (some USD 200-300 should suffice) and provide impressive sound. They usually are/can be equipped with remote control, FM radio and CD player, as well as some kind of input for audio from another source. However, for your use there may be limitations (depending on the system):
- no pre-amp for a record player (a record player needs additional amplification, modern amplifiers often do not have this built in so you’d need to buy a separate phono pre-amp)
- no facilities for multi-room set-up
- no streaming (although some systems may have this).
So if those uses are important to you, I’d suggest to start with a basic core system that offers most of the functionality you want, such as the Yamaha multi-cast system suggested above, and add those elements that you need in addition. The quality of such a system is higher than a micro set, but of course you pay for it. The multi-room connectivity in particular may be fairly costly if you need to add a unit with speakers for a separate room. I’m not sure whether Yamaha multicast has an option for a simple ‘remote speaker’ with built-in reeception for the audio from the main unit.
Alternatively you may consider a system such as Bluesound, which is indeed hifi with a good streaming app and multiroom options.
If you start with streaming, you should be aware that the most important part is not the hardware but the app. Many large manufacturers have streaming apps that are not user-friendly or miss basic functionality. Bluesound is a positive exception; I believe Yamaha is also good.
I’d strongly suggest to also consider buying second-hand. In particular speakers, record player, and phono pre-amp should be available cheaper, as often people ditch their stuff. Only problem is shipping.
I seconded the Yamaha Multicast suggestion as that has multi-room functionality built-in, while I’m not sure how good the functionality from other manufacturers in that respect is. In theory you could consider other fairly cheap amp systems (such as Denon CEOL, but the streaming app is horrible), and add multi-room and streaming and phono input in another way if need be, but that would require you to study on how to achieve this, and it seems you’d prefer to avoid that.