I really don't understand your question
That's OK. In the absence of an explanation, the title of the thread and the body of it bear little resemblance. A non sequitur.
There is no 5 wpc amplifier used in the test or in any subsequent discussion.
Paul Klipsch was right - What the world needs is a good 5 watt amplifier
For those who are questioning whether a low power high quality amp would be able to properly drive any speakers I've recorded a short video demonstrating very high SPL level from a speakers with average sensitivity. The video is of very low audio and video quality as its recorded from my smartphone. However, the microphone used for measuring the sound pressure is MiniDSP UMIK-1 and the software used is REW (Room EQ Wizard). During the tests the amplifier didn't show any hint of stress of distortion
The speakers used in this video are Sonus Faber Olympica II and the integrated amplifier is Pass Labs INT-25. According to some third party reviews the Olympica's are thought load for the partnering amplifier as their sensitivity is averagely rated (88db) and the impedance curve drops down to 3 ohms in the bass region with a estimated EPDR (the point where the impedance curve is intersecting with the phase angle) of 1.6 ohms. The pass labs is rated at 25wpc @ 8omh and is said to be stable down to 1 ohm doubling its power at 4 and 2 ohms. According to the manual it can deliver 200wpc @ 1ohm before the protection circuit is activated.
So, the point of the video is to show that the Pass with its poorly rated power (25wpc) can drive even demanding speakers to insanely loud levels without any sound degradation.