Hi,
I thought Rajiv would explain it completely ! but no problems !
The Power of an amp is always dependent on the speakers partnered ,Meaning if you a speaker with relatively less sensitivity say 86dB then you require more power to drive them to the same decibel level as high sensitive speaker say the Altec which Rajiv owns ! its much more complex but without confusing you here's the simple answer.
for every 3dB increase in the speakers sensitivity the Amp power is reduced by almost half to give a desired output or decibel level ! so if the Amp is say the SET 2A3 with 3 watts then 99dB sensitive speakers as Altec at 3 meter listening position would reproduce 91 decibel (if you know how loud is that) of peak sound with 3db Amp headroom !! the same SET Amp if connected to a speaker of 86dB sensitivity then you would only get 78 decibel of peak sound !
Hope you Understood Ruenigma
!!
Here's the formula !
Equations used to calculate the data:
dBW = Lreq - Lsens + 20 * Log (D2/Dref) + HR
W = 10 to the power of (dBW / 10)
Where:
Lreq = required SPL at listener
Lsens = loudspeaker sensitivity (1W/1M)
D2 = loudspeaker-to-listener distance
Dref = reference distance
HR = desired amplifier headroom
dBW = ratio of power referenced to 1 watt
W = power required
This does not mean that a less sensitive speaker is inferior in quality of the sound reproduced
Regards.