I am currently running two Antminer S5 units in an area taking advantage of the heat they give off. I am thinking about getting the S9 to actually be more efficient while getting some heat from it too, my only concern is the noise level of the new unit vs. that of two of the S5. Could anyone that has owned both S5 & S9 let me know how the noise level of (1) S9 unit would compare to (2) S5 units?  I obviously know the S9 has a lot more power & and is louder overall, but is it still louder that two of the S5 going at once next to each other?

Any recommendation on another route to go would be helpful also.  I know the Antminer R4 are quite, but do they give out decent heat as well?