The Allen & Heath looks appealing, especially with. I’m not knowledgable about mixers. I only have a soundcraft compact 4 which I have a mic and my bass or guitar connected to. I think I have it connected right. I got confused when Simon had that video showing his studio and how he controlled the levels from the computer via the mixer etc.
I think he has the outputs from his soundcards routed to his mixer, thus being able to control the ‘volume’ from the mixer faders. It looks to me that he records into the box, but then physically mixes with his Mackie 8 bus + outboard.
as far as mixers, you can’t go wrong with A+H, Soundcraft or Mackie. They are the best budget mixers in terms of preamps, channels and quality you can buy.