I recall here again your schematic:



In circuit "H", a pi-filter containing a ferrite choke should really be used! This is not a question of supply current, to neglect it or not, but of interference the micro produces. A simple RC filter does not at all show as similar hugh dampening performance as a good LC-pi-filter offers.
Also, the ground connection of analog and digital ground should be done next to DAC. Separate analog and digital grounds as it's shown here:



(In this simplified schematic the filtering of digital section isn't shown!)

It's impossible only by the help of a LC-filter to filter out 100Hz ripple as properly as a voltage regulator does. Even putting two or more LC-filters in series will not help. You would need lots of hugh chokes to achieve the same performance as a simpe regulator yields.
So, if your analog section needs very low ripple on Vcc, then either you should use the 5V regulator to supply your analog circuit, or give it an own regulator.
Running analog circuitry with a non-regulated supply voltage isn't a good idea. Might be acceptable for some battery powered applications, but mains transformer powered circuits will mostly need a regulator.

Kai