Post

do you need attenuators and multiples in the rack yet - probably not

I'd use the attenuators and multiples to split and control modulation sources of the analog 4. Maybe I don't need them yet in this minimal setup, but they were cheap anyway, and I reckon they will become handy later if the setup grows.
-- SolNoctis

Personal opinion : attenuators are a total waste of money and, more importantly, HP. Instead get an Attenuverter + Offset module.
- Cheap option : Ladik U-012 Dual Attenuverter + DC
- Three channels and it's also a mixer : Happy Nerding 3 x MIA
- Similar but different : Frap Tools 321
- More flexible routing and it also a 4 quadrant amplifier : Befaco a*b + c
If you really want three passive attenuators you can find much smaller and cheaper version alternatives the Behringer inhere. (Cheaper than Behringer?! True!)

In my small setup, I never had a use for multiples -- I use stack cables. OTOH switched multiples are a whole different proposition. This one is no bigger than the one you picked, also has 8 ports and has 3-position switches for all the outputs. It's a kit but it is super easy, even I managed it.