QC35ii slight hiss during ANC

[Rdefonseka]

I notice a slight hiss when ANC is on regardless of the level eg high or low ANC. The hiss disappears when ANC is off

This is a brand new pair. The app indicates the firmware is up to date and am connecting to an IPhone

The hiss is very subtle but having noticed this I can now discern it while music is playing

[Horseshoes]

I am currantly comparing my QC35s to a pair of Sony 1000 MX3s. The Sony has a more promanant hiss than my Bose. The Sony sounds more like a fan running in the background. The QC35 hiss is almost none existant.