Yes of course, a microphone connected to a spectrum analyzer will distinguish between amps as to which reproduces 'bloom' or accurate timber. Perhaps you can direct me to the 'bloom' and 'timber' test charts for different amps? I am not aware of any tests of audio equipment which compare the output of a component (variable) in a test system, on the one hand, and live music on the other. If you put a microphone in front of an orchestra and direct the output from microphone to a frequency analyzer, undoubtedly somewhere in the hash of it all there would be indicia of the 'bloom.' But, you wouldn't be able to tell me what test results correspond to the bloom effect, could you? Who cares whether the tested phenomena has been registered on the spectrum analyzer if you can't individuate one quality from another on your analyzer ... which sort of gets us back to the human ear, which might not be as sensitive as a good microphone, but I assure you that its associated processing hardware and software is infinitely more sophisticated than your spectfum analyzer.
