To be precise, 8 watts is 10log(8/3) = 4.26 db greater than 3 watts, everything else being equal. To put that in perspective, the classic rule of thumb is that a difference of 10 db (10 times as much power) will be subjectively perceived as "twice as loud."
Regarding "everything else being equal," though: Assuming that those power ratings are based on an 8 ohm load, to the extent that the speaker impedance varies from 8 ohms at various frequencies, and to the extent that the output impedances of the two amplifiers are not the same, that 4.26 db difference may change significantly in either direction. Other design-related differences between the amps, such as in their power supplies, of course can also affect that value significantly, depending on the impedance characteristics of the speaker, the dynamics of the music, and other variables.
Sebrof, great job helping out! Rebbi, continued good luck.
Best regards,
-- Al
Regarding "everything else being equal," though: Assuming that those power ratings are based on an 8 ohm load, to the extent that the speaker impedance varies from 8 ohms at various frequencies, and to the extent that the output impedances of the two amplifiers are not the same, that 4.26 db difference may change significantly in either direction. Other design-related differences between the amps, such as in their power supplies, of course can also affect that value significantly, depending on the impedance characteristics of the speaker, the dynamics of the music, and other variables.
Sebrof, great job helping out! Rebbi, continued good luck.
Best regards,
-- Al