Phase Linear as well as a lot of other manufacturer's measured the "frequency response" of their power amplifiers at 1W. So 1W into an 8 ohm load would be 2.83V output. (NOTE: An input voltage of around 78-81mV should get you there.) Phase Linear's frequency response spec was +0/-1dB at 1W. A White Oak Audio Rev E board with back-plane boards should go down to 4 or 5Hz easily and top out at around 42kHz +0/-1dB. The Phase Linear distortion spec is from 20Hz to 20kHz at rated output. A 700 series 2 amp rated at 360 watts a channel into a 8 ohm load would be 53.66V. The distortion spec will look pretty good at 1kHz. You should be checking the amp at 20kHz both channels driven to rated output. Then let us know what you get. Worst case scenario for most amplifiers will be at 20kHz. The spec for a series 1 700/700B is +/-.25%. The spec for a Phase Linear 700 series II amp is +/-.09%. NOTE: Phase Linear's 700/700B and 700 series II service manuals also allowed for the use of a 80kHz filter on the distortion analyzer.