9k+ albums, say approx 350MB per standard CD equates to 3.15TB.
Your backup and export will be pretty much the same size. I would also use two disks.
Sooloos, Roon, G series (with LPS upgrade), 800 series (with LPS upgrade), HD621, AC200, Prime and PS, DSPs old and new.
Purdeys, Moke, Leica, 'Blad. Only the best.