I understand that some very quiet ‘pops’ can occur when the Amp in a active speaker is engaged/disengaged - so that aspect is probably nothing to worry about and possibly normal operation, particularly if you have to put your ear to the speaker to actually hear it. I have heard the pop noise with a Sub (gen3) in the past, but like you, had my ear right next to its aperture. 

A  minor hum can come from the power supply/power source to the device - particularly whilst waiting for the Amp to get going - it’s a case of whether the hum is excessive, or not. My own thoughts are if you cannot hear these things from a few feet away (say, one metre) then I personally think all is likely to be okay, but if you hear these things beyond that distance, then it might be worth speaking with Sonos Support.

The thing with these kind of noises is it’s difficult to sometimes not hear these things, once you have listened to them and you may think you hear them, even at a distance, so I think it’s sometimes worth getting others involved to see if they can hear anything when they’re a few feet away, but perhaps don’t mention what the noises are and just see what they say.

If the issues persist, then it maybe best to submit a Sonos system diagnostic report from within the Sonos App, note it’s reference and then contact/chat with Sonos Support Staff via this LINK and see what the Staff can perhaps suggest to resolve the matter.

Personally speaking I think all is probably okay here, but it may depend just how loud these different noises are. If you find you can’t live with them, then it’s worthwhile getting in touch with Sonos Staff.