ah, its standard specs ? the shown heatsink looks a bit small for that
but this 1200watt from Ground Sound I would trust more
quote
The maximum power output depends on voltage supply, heat sink and load conditions. Recommendations: Voltage supply of + / - 95V, heat sink less than 0,2 K / W and minimum load of 1,5Ω.
I visited Ground Sound products page. SMD resistors are used in their amp boards. I couldn't figure out the size of them. I guess they are 0805.
I experienced resistor thermal distortion when measured a 150 W/8R amp. The feedback resistor was 0.25 W. Abnormal high level distortion occurred for output level higher than about 80 W. Distortion cleaned up with the feedback resistor replaced by a 0.5 W resistor.
I also noticed the PA6CC and PA3CC distortion vs output charts are ruler flat from right all the way to clipping point. An interesting performance! The amp are distortion limited for all output level. It doesn't seem okay to me.