[nigelpry]

Regarding analog to ADAT, yes there are way better convertors, but it is what your budget will handle.

The newer Behringer ADA8200 is better than the original ADA8000, the MIDAS mic preamps in the newer model are better, and at least as good as the 003.

One thing to be very careful of, and something that has caught many people out, the XLR mic socket and TRS jack socket are both active at all times, whereas most kit is switching, where plugging in a TRS jack breaks the XLR circuit. DO NOT have both XLR and Jack plugs connected to the same input at the same time, depending on what is connected that can badly affect noise levels.

I suggest using mics via the Apollo and use the Behringer (or something more expensive if you can afford it) for the keyboard outputs. Bear in mind that the keyboard outputs are probably the weakest link in terms of noise, but with correct adjustment of gain levels, coupled with some simple eq on the channel in your daw, you will keep it down to a level that shouldn’t trouble you.

As for cheap AES to S/PDIF convertor, in the UK we have this ...

https://www.studiospares.com/studios...ter_465760.htm

and it only costs £34.99!