I recall this, but it doesn't answer my question though >_> I didn't ask if the amp section is good, I was wondering how good is it. Obviously we consumers can't know as there is no way of testing it in separation of the DAC.
One can do some math to extrapolate the noise level (by assuming noise from DAC and amp are uncorrelated): a 3 dB increase in noise would imply equal noise between DAC and amp, a 1 dB increase would imply about that the noise from the amp is about 6 dB lower than that of the DAC, if the amp's noise is 10 dB lower than that of the DAC, the total noise is about 0.4 dB higher and if the amp's noise is 20 dB lower than that of the DAC, the total noise is about 0.04 dB higher than the noise of the DAC.
Thus, the noise level of the amp section is likely between 10-20 dB below that of the DAC.
Distortion is a bit more difficult to calculate because it depends on the correlation between the distortion of the DAC and the amp. If one harmonic is of the same level and in phase, the harmonic in the DAC+amp output is 6 dB higher while if the levels are still the same but the relative phase is pi/180 degrees (half a cycle), the harmonic from the amp cancels that from the DAC. If the amplitudes of the harmonics are not the same, things get even more complicated.
However, the same math as that for the noise level can still be done assuming all relative phases are equally probable, i.e. the harmonics can be treated as uncorrelated in expectation. Thus, the distortion of the amp section is expected to be 10-20 dB below that of the DAC.
Anyways, maybe
@MC_RME could drop some ball park numbers for the amp sections.