I ran my 3255 eval board with the SE inputs, and I never could hear harmonic distortion or noise.
The distortion number is still rather low with the side 1 THD+N measurement of 0.013%. There is a bit of difference from the side 2 measurement of 0.0049% due to improper ground plane layout I suppose, but you think you could hear the THD+N number that low with 100Hz at 20 watts?
The op-amps convert from SE to differential, because the 3255 chip only has differential inputs if I recall correctly.
I'd try the SE inputs, and see if works out for you. If it's more convenient to input the eval board with differential inputs, then I would go that route.