@Veri , different systems are different by definition of being different. How's that for circular logic !!!
I had a pair of high efficiency 101dB 8-Ohm horns in the 80's and an amp combo that you could plainly hear constant noise when paired. Pairing the same amp with average efficiency speakers of @ 92dB or less, the noise was not appearant. Pairing the high efficiency horns with a different amp the noise was not apparent.
The high efficiency horns either revealed/highlighted something the other speakers masked or the amp irritated something in the high efficiency horns that it did not irritate in the average efficiency speakers.
I did not have the means to measure/identify the specific problem so I can't attribute the cause to the amp, the horns, something upstream being passed/blocked or combination thereof, but what ever it was, there was an obvious audible noise level difference between the 2 pairings.