IF the question is about ferrite beads on the output of a switching supply, the answer, is YES.
But beads are too little - you want LARGER inductors. at least a PI filter, and maybe several sections of PI filter...
Do not use ferrite beads on MOST signal carrying wires, in most cases - there are exceptions. Ferrite beads have nil effect in band for the most part, but I still don't prefer them in circuits.
For your switching supplies, I would suggest another stage of voltage regulation AFTER whatever the supply provides. If you end up with voltages 2 volts lower than spec, but far cleaner, lower in noise, that is far better.
Use low drop out types, low noise types for this application.
Watch your grounding.
It is a good idea to put a filter on the input of the switching supplies, as there can be some reflected noise sent back out the lines...
much on the web about DAC design, low noise design, low noise regulation, grounding, bypassing, power supplies, look around! :- )