You are not totally wrong at all. In theory, everything else being equal, balanced should give you better signal to noise ratio regardless of the length of the interconnects. My comments are based on the following:
1. For whatever reasons, every bench tests I read in the past showed using balanced connections vs unbalanced of the same amps ended up with slightly worse SN ratio. I can only attribute this to factors from real world practical use, that the theoretical advantage of better SN ratio (by 3 dB) could not be realized.
2. Even in the rare cases (just assume), when you might get the maximum theoretical 6 dB advantage in SN, if you look at Emotiva's and Monolith's SN specs, their unbalanced SNs are well above the level where even human with super hearing could not tell the difference. Note: If you do have long runs of cables, then obviously balanced is the way to go, and in some cases, the only way to go.
3. Again, in theory, amplifiers that offer input to output (end to end) fully balanced (differential configuration) are supposed to have better distortion specs, but there are counter points:
a) The THD+N and IMD specs of most decent amps including Emotiva Gen3's and Monolith's are well below the level where even humans with super hearing could not tell the difference.
b) Emotiva's older XPR amps were supposedly trully/fully balanced, but I highly doubt the XPA Gen3s are, because they would have said so in their features/specs. Even if they were, I do not believe it would make any difference, in fact I would prefer that they are not fully balanced at their price point for the obvious reason (cost!!). You don't get something for nothing..
Monolith's do offer 2,3,5,7 channels, there are sales right now for the 3 and 5 channel ones.
https://www.monoprice.com/pages/monolith
You can get the 3 channel one for $899 and then get something smaller (e.g. from Outlaw or Emotiva) for the surround channels.
