When looking at speaker/amp combinations
90db speakers at 1 watt will generate:
93db @ 2 watts
96db @ 4 watts
99db @ 8
102 @ 16
105 @ 32
108 @ 64
111 @ 128
112db is ultra THX
110db is THX
You have to increase by 10db to get a perceived doubling of loudness. Therefor, you really won't hear a difference between 100 watts and 140 watts per channel.
Also, not all amps double wattage output if you go from 8ohms to 4 ohms.
90db speakers at 1 watt will generate:
93db @ 2 watts
96db @ 4 watts
99db @ 8
102 @ 16
105 @ 32
108 @ 64
111 @ 128
112db is ultra THX
110db is THX
You have to increase by 10db to get a perceived doubling of loudness. Therefor, you really won't hear a difference between 100 watts and 140 watts per channel.
Also, not all amps double wattage output if you go from 8ohms to 4 ohms.