I think the easiest way would be to get a new surround receiver with 2 zone operation.Instead of sending Zone 2 signal to an amplifier send it to your recording device..
Google search :Can you hook up a tape recorder to Zone 2 on a surround receiver?
Result:
Yes, you can connect a tape recorder to Zone 2 on an AV receiver that has a Zone 2 output connection. The Zone 2 function allows you to send an audio signal to a separate system in another location.
Receiver having audio out jack for recording analog sources
Need to replace my failing home theater receiver TX-NR809 and am finding none of the receivers being sold have the capability to output its inputted source signals to a recording device such as a CDR or tape recorder. I use this to transfer albums from LPs, Cassettes, or Reels onto CDs that I then insert into my CD/DVD player plugged into my MacBook, so that they will be available to hear on my iPhone or through my iPhone to my Home Theater speakers via a bluetooth adapter connected to my receiver. Can you recommend a recent receiver that I perhaps have not yet found or recommend an easier way of transferring my albums to my iPhone such as via a combination of other equipment? I do use Spotify to stream some albums when I can, but prefer storing the albums on my iPhone.