I use this amp NPA 220 for a little less than 1 year and I am very satisfied, 2 amp used in both 4 ohms 8 ohms or bridge to get a good amp is no puissance.Cet a high quality yet good value qualitprix (can be heard by the grsillement hp in a power-up). Prior to this amp I had an amp 4 times less powerful but with a higher sound quality leve, I pay the same price avai for lower puissance.J 've made this choice a matter of money, I pay a price the quality above.