Fifth test. I did this to see what exactly was happening. Were the output inductors struggling with the load? No it seems as the same trend to high frequencies is the same as before,, but this time into a 4.8 ohm load. This was really pushing the limits of the PSU where the voltage sag sometimes caused a tiny amount of clipping, hence the roughly more 'wobbly' look to the curves. This represents 124 watts into the 4.7ohm test load.