How much separation can you get from a 6" phone though? I mean would you notice it, or would it be better to have a single speaker which is twice as good as two rubbish ones? I don't know the answer myself.
You would be surprised at how much better Nexus 6 speakers sound compared to an S7/OP3/iP6 etc.
2 reasons - Front facing for clarity, stereo for imaging and sound steering.
And goes without saying decent drivers are needed to begin with. I watch a lot of YouTube so FFS come in handy for me. So much more enjoyable.