Performs in what way? If amp B is a very poor design, is broken, or was intentionally voiced that's possible.Right, so if amp A performs better than amp B then effectively amp A could, or maybe should produce a better soundstage.
Properly designed modern solid state amps don't exhibit those variations.
"Vastly exaggerated in importance by the audiophile press and high-end audio dealers. In controlled double-blind listening tests, no one has ever (yes, ever!) heard a difference between two amplifiers with high input impedance, low output impedance, flat response, low distortion, and low noise, when operated at precisely matched levels (±0.1 dB) and not clipped. Of course, the larger your room and the less efficient your speakers, the more watts you need to avoid clipping."
Peter Aczel