@Dave-Williamson Depends on what your into. There are units that bill themselves as multi-channel AD/DA converters that happen to have usb and/or firewire interfaces, like my Mytec 8x192. When I plug its usb or fw interface into a computer, it shows up as a bunch of interfaces that can be recorded or played... I use its analog monitor outputs to feed by monitors. I used to use it for high res audio recording to the computer but not so much anymore. Better easier choices now, like flash recorders. Also, it doesn't have mic pre's. If you want something to record with mics, you'll want mic preamps built in unless you already have a bunch. Focusrite and RME make some nice ones like that which they bill as audio interfaces but they can also be operated as standalone mixers. I have a 4-channel Focusrite Claret that I use for streaming because its built-in mixer and mic pre's make an additional mixer unnecessary... they also make 8-channel versions and their Scarlett line is pretty economical. RME's are similar but cost more and personally, I don't think my UCX sounds as good. But it does have more flexible internal routing and mixing. There are also units that bill themselves as mixers and also have usb interfaces. These usually have any number of mic inputs. I use a Berhringer mx32 for live theatrical sound and it has a usb interface and driver that causes all its inputs to appear in a computer as audio interfaces. Used it a few times to record to a computer with Reaper and didn't really care for it. They also make smaller units with and without all the sliders that are very popular in live sound due to being able to be remote controlled with a cell phone app from anywhere in the venue. Ended up getting a usb option card for my mx32 that records all the input channels to a usb stick instead of to a computer. Most convenient these days are multi-track flash recorders that have mic inputs. I have an aging Sound Devices 788T that has 4 mic + 4 line inputs recording to flash + hard disk... these days I use it to record almost all my sound when shooting video. More contemporary units from Zoom and Tascam are probably more advanced, less expensive, and might even double as audio interfaces.
The Zoom F8n can double as a interface and record to two SD cards, It even can record BWF (PCM) files on one card and MP3s on the other, including internal stereo mixes. I am not sure about the lower priced Zoom recorders. If you do not need a portable recorder, an multi-channel sound interface would be much lower cost than the F8 film sound recorder or one from Sound Devices or Zaxcom. I too have an aging SD 788 and 744 and picked up the F8n for secondary and back-up.