Aquí podemos ver la diferencia entre el X1200W y el X4200W:

Denon AVR-X1200W A/V Receiver Review Test Bench


0.1% THD 1.0% THD
2 Channels Continuously Driven, 8-ohm Loads 112.8 watts
 126.1 watts
2 Channels Continuously Driven, 4-ohm Loads 139.2 watts
 164.3 watts

Denon AVR-X4200W A/V Receiver Review Test Bench


0.1% THD
 1.0% THD
2 Channels Continuously Driven, 8-Ohm Loads 124.3 watts
 149.2 watts
2 Channels Continuously Driven, 4-Ohm Loads 215.9 watts
 239.7 watts