Depending on the scale of production, a minimum of 8 GB RAM that is upgradable as your needs go up. Starters that do light mixing, audio editing etc with some instruments will do okay with 8 GB plus tops. Medium scale sound engineering and production will require 16 GB of RAM to support many MIDI files, multi-instrumental tapes and mixing. For large scale production and music composing, 32 GB with an upgrade option will be required to run and mix 100+ tapes that are all MIDI. It would be best to start small, and upgrade slowly, rather than investing in a laptop with huge RAM at one go, unless you are sure it will be required and fully utilised.