So if i where to buy the amp u suggested second hand, i would be able to turn up the voulme?
It has around 4 times the power.. so yes higher volumes would be achieved. Instead of the amp 'clipping' and turning itself off to prevent damage the limiting factor would become the sensitivity of your speakers and their power handling capability - rated to around 75 watts iirc?
From the MB42 operating instructions..
The MB42 can be used with amplifiers between 15 to 100 watts per channel as long as reasonable care is exercised. If there is audible distortion, turn down the volume until the distortion goes away. Never allow the speaker and amplifier to play for more than a few seconds when there is audible distortion.
So the Lepai is definately right at the minimum end of the speakers power handling scale.
If the numbers are correct, the MB42's sensitivity is rated at 85dB 1W/1M, so with your speakers at 1 metre listening distance, your lepai should provide enough power (Very generous estimate @ 15w per channel and if it wasn't clipping) to make the MB42's produce around 99.7dB?
With a 80W per channel amp, a safe 70W per channel input into your (75w rated) speakers at a 1 metre listening distance should produce around 106.46 dB.
At 3 metres listening distance these numbers change to aprox 90.26dB and 97.25dB respectively.
That might not sound like much of an increase but remember that each 10dB increase is perceived as aprox double the volume.
Try a beefier 5A power supply first, the 2A one simply does not supply enough amps for the amplifier to produce the claimed 20 watts.
