The Mission 529 and 529HC are two of the lowest noise pedal board power supplies available. Check out the test results to see noise measurements of the 529 compared to some other isolated pedal board power supplies.
The traces above show a 9VDC power output from the Mission 529 compared to another brand of isolated power supply using an external AC/DC switching supply. For reference there is also a trace from a large, premium power supply with an internal toroidal transformer. Toroidal transformers are sometimes quoted in systems specs as being important for low noise.
As you can see from the traces, the 9VDC from the 529 and toroidal supply are virtually identical, whereas the other switching supply is somewhat noisier.
The second set of traces above shows what can happen when switching noise passes into the audio path. In this test, two power supplies are powering a compressor pedal. A test signal representing the guitar is generated at the input and measured at the output.
You can see in the first trace of another brand of power supply that there is some noise superimposed on the audio signal. In the second trace, where the 529 is powering the effect pedal, this noise is removed.
When used with batteries, the 529 high efficiency converters provide long battery life and minimal wasted energy. Exact run time depends on battery and total power consumption of pedals. As an example, run time for a pedalboard drawing 500mA with a 10,000mA/h USB battery pack is over 5 hours.