"How can you make statements in regards to amplifier performance/musicality when you are not using the same speakers to compare them (and maybe not even in the same room)?"
You have a fair point in principle but its certainly better than making statements/comparisons just based on on-paper measurements. If you spend the time to go and listen to different component combinations instead of looking at the specs, then your ears will be able to tell the difference. For example, I have heard the GE Reference speakers paired with other amps/preamps like McIntosh and Rogue tube amps and they sounded nowhere as hyper detailed and dry. Some people may prefer that sound.
You have a fair point in principle but its certainly better than making statements/comparisons just based on on-paper measurements. If you spend the time to go and listen to different component combinations instead of looking at the specs, then your ears will be able to tell the difference. For example, I have heard the GE Reference speakers paired with other amps/preamps like McIntosh and Rogue tube amps and they sounded nowhere as hyper detailed and dry. Some people may prefer that sound.