Originally Posted by scud133
put your ear closer
(or replace your speaker with a more efficient one that puts out more dBs with the same power/wattage)
The best way.
Watts are a measure of power, dB are a measure of relative loudness and varies with the efficiency of the speaker, as well as all the other data from the amp itself.
A large part of why 30 tube/valve watts tends to sound louder than more modern transistor amps is that the oldies had far more efficient speakers.
I have an 11 watt Wide panel deluxe with a little 12" high efficiency Celestion from way back in it.
That is one loud little amp and mostly because the speaker is very efficient.
Look at the dBW figures in a speaker`s specification and choose one that gets as close to or higher than 100dBW as you can.
This figure indicates the loudness level acheived at a distance of one metre from the speaker for a 1watt @ .75 volts (0dBv "standard" ) input from the amp.
This is a gross over simplification but will hopefully give you the general idea.