Let me put an end to this rumor right now.
There is absolutely nothing true or accurate about this comment. I believe it was due to something he or a friend read in a review in BGM magazine where they tried to measure the power on a 1200 with a poor (unregulated) AC power source, and were not able to do so accurately. The larger the amp, the greater the deviation from rated power due to the Vsquared factor in the power equation. Unfortunately we were the first large amp tested with the improper procedure and their tech didn't recognize the importance of input power voltage in the measurement of power and it's (squared) effect on the results
When I analyzed the test set-up, they did not follow the industry standard practice of using a regulated or fixed input voltage and for large power amps of all brands and models, this MUST be done because the output power on all conventional amps falls with a dropping power source voltage. Other major issues were also uncovered when analyzing the test procedure, Tom and his crew have been revising and revisiting their approach to testing and we hope to discuss this more at NAMM to try to come up with some tests that relate better between lab and real world performance conditions across all brands and especially with the advent of the newer class D products, amp types.
The 1200 delivers at least 1200 watts RMS into 2 ohms and 1000 watts RMS into 4 ohms with an input power of 120 volts (maybe slightly more at 240 volts). It will also function without going into protect mode down to <105 volts.
Regarding amps and low voltage protection issues, any (quality) amp should protect itself against extreme low voltage conditions. Less than 105 volts (excluding Japan) is the commonly accepted low line condition threshold, and what most manufacturers are doin gis improving their protection schemes to improve product reliability which allows (many of) them to increase the duration of their warranty. Look back 10 years and you will see generally higher industry failure rates and shorter warranty periods. With the industry trying to improve reliability, the newer amps will generally do a better job of protecting themselves from things like low line conditions, resulting in the amp shutting down and protecting itself rather than failing. Which would you, as an owner, prefer? Especially ifthe warranty was shorter and you were responsible for the repair.
If you encounter a line voltage falling below 105 volts, you really should be cautious about plugging anything of value into it. Don't forget that line voltage must be measured under load, and excessive foltage drop is not uncommon with sub-standard wiring and extremely long or undersized extension cords.