If you only use a 1/4 of the amplifier range, this isn't a waste. If you drive an amplifier too hard it will increasing distort your audio. Common mistake of a lot of sound techs, they use undersized equipment and turn it up to the max and produce crap audio. I am not sure if this is still true or not but long ago I was given the advice for for analogue outputs to set the computer to 75%. This was suppose to be an optimal level for the sound card DAC, maximising (or is minimising I don't recall) the volume and signal to noise ratio. Then use the external amplifier volume as required.
