Taking the (+) signal and running it through an inverter to generate the complementary (-) signal is fairly common and one of the schemes I refer to as "quasi-balanced". Since noise is uncorrelated signal doubles but noise goes up by ~sqrt(2) so there is some benefit. Since each amp depends upon the single-ended input the CMRR and PSRR may not be as high as a truly differential design, and there is phase lag through the inverting path relative to the non-inverting path. Hopefully not enough phase shift to matter at audio frequencies.
Routing the ground return for each side of the headphones is not balanced to me; it is simply two independent single-ended runs. Yes, it isolates the signal paths to each side, but does not provide better common-mode rejection etc. Looks like marketing to me.
Routing the ground return for each side of the headphones is not balanced to me; it is simply two independent single-ended runs. Yes, it isolates the signal paths to each side, but does not provide better common-mode rejection etc. Looks like marketing to me.