When I have some free time I will pay the dealer where I bought my MCA years ago a visit, to find out what the discount factor is for the STR. It is possible that their prices are more negotiable than the budget oriented MCA series.
By the way, I spent lots of time to search out the definitions of "continuous" power rating for audio amps. I did download all I could find, but one that is easy to read is in the TI article linked below:
On page 1, it says:
"For an audio signal, the voltage is in Vrms (root-mean-square), the power is referenced to a frequency of 1,000 Hz, and the load is usually referenced to a resistive load. Thus, the power obtained is the average power that the amplifier can sustain. The FTC requires further that the amplifier be pre-conditioned at one-eighth of rated total power output (for a multiple-output system, all channels are on) for one hour using a sinusoidal wave at a frequency of 1,000 Hz. The power spectrum measurement is then collected with two channels at maximum rated power over the audio frequency range of 20 to 20,000 Hz, in ambient still air of not less than 25°C, for the duration of not less than 5 minutes.
Some manufacturers use an average power rating, but at a higher distortion ratio obtained by amplifying the original input signal to a level where clipping occurs. At 10% THD+N, the average power rating is higher than at 1% THD+N. For Texas Instruments PurePath Digital power-stage data sheets, both unclipped and clipped power ratings are measured."
So it's 5 minutes or longer according to this source. I read different duration from other sources, that also referenced FTC, EIA etc., problem is, for the same standard, there are different versions. I also focussed on those I could download for free. On of these days I would bite the bullet and purchase one or two just to satisfy my curiosity.