how little ripple is enough?

0.002vac is the resultant ripple at my preamp after the second 10M45S chip. at B+, it was 0.009vac, and between the two 10M45S, it was 0.008vac.

Seems like one chip alone is not enough. Two together resulted in around 77% drop in ripple in my high voltage supply to my preamp.

I guess 0.002vac is good enough?

The measurements can be seen here.