Poor earpiece quality, finding "sweet spot" and hissing topic

Hi all

Picked up a Nexus 5 recently (latest model latest revisions) and love the phone but am having issues with the earpiece quality.

I have to constantly move the earpiece/headset around to hear the person and find the "sweet spot", or they fade in and out.

Also I notice a hiss at times.

Reception and earpiece quality overall just don't seem good.

I have iPhone 5, galaxy s4, and htc one and none have these issues.

I am on rogers wireless in Montreal.

Does anyone else have these issues ?
Any idea how I can resolve them ?
Some have suggested changing kernel ?

Any help would be much appreciated

Thanks in advance