I have a review of the original 405 in a 1979 "Audio" magazine. While the amp was rated rather strangely in terms of many of the spec's, it went measurably down in power output going from an 8 ohm to a 4 ohm load. From what i can remember, we are talking about a 25% reduction in power output whereas in theory, it should have been a 100% increase. I wonder how the 405 II stacks up in comparison ???
Funny thing is, i was just communicating with someone that is using a 405 to drive a large set of E-stat's that drop down to about 1 ohm or so. They told me that the 405 was doing a better job / would play louder with the E-stat's than their multi-thousand dollar mono-blocks that are rated for over three times the power. All i can say to that one is "go figure"..... : ) Sean