The Mute Audio GrubDAC
All electrolytics (polymer and aluminum) have leakage current. This is the current that passes through the capacitor to keep it charged. It is given in specs as a current rating in microAmps (uA). However, apparently this current makes a capacitor "noisy."e;
You can read the formula off the datasheet.
For a Panasonic FM: I <= 0.01CV
For a United Chemi-Con PS-A: I=0.2CV
So a FM is an order quieter than a PS-A. Now how does this affect the grub? Well C1, C5 and C15 are part of a low pass filter to keep out noise. We want the largest cap possible to get a good effect from the ferrite/capacitor combo, but we want quiet as well. The PS-A gives us larger value, but is noiser.
So a tweak, for those not building a cable DAC would be to use aluminum electrolytics. Panasonic NHG is available in good values (470uF in a 6.3 x 11.2) for all three positions. FM and FC are available in 330uF. Nichicon at Mouser also has quite a few good options (UFW, UKW)
Note that this would also apply to the Bantam C12 position. Being a mid-rail decoupling cap, you want low noise here.