There isn’t too much. When I had my commercial studio I would track through tube and transformer output mics, to a transformer coupled multitrack, mix with tube and ss transformer coupled gear (on individual tracks and buses) and mix to a transformer coupled 2 track tape machine. It sounded big and organic, but it still sounded clear and ‘hi fi’. Sometimes if I counted there could easily be over 20 transformers from mic to final two bus processing that a single track would go through.

Up until a lot of chip based gear was prevalent (starting in early 80s) this was the norm. All the classic albums (including jazz although processing was probably minimal) were like that as there seemed to be very few transformerless gear produced at that time.