This should probably be discussed in a thread devoted to what qualifies a mono-block to be a true mono amp.
There doesn't need to be a thread devoted to discussion what qualifies a mono-block to be a "true" mono block.
Amplifiers are broken down into categories based on topographic (or class) and number of channels (there are more ways to break it down but I'm just going to use these for now).
Class consists of the type of circuitry that the amplifier uses to produce power (such as D, A/B, B/D, A/D, etc., etc.)
Number of channels consists of how many separate channels the amplifier has. For instance a mono-block has 1 channel of output (takes the left and right channel and sums them into 1 mono channel), a 2-channel which is "stereo" as it takes the left input and right input and reproduces them independently. 4-channel is the same thing, it takes in a left and right input for the front and the same for the rear, all independent. Finally there are multi-channel (which consists of 5, 6 channel, etc.)
A "true" mono-block is one that has 1 channel regardless of what impedance it is stable at. Just because an amplifier (such as mainstream companies) have a mono block that is 2 or 4 ohm stable, doesn't mean it's not a true mono block. ****, if the amp is .25, .5, 10, 24, 68 ohm stable, as long as it has one channel of output, it is considered a mono block.
There are a lot of amps like Kenwoods and Alpines ''mono-block'' amps that claim to be able to be wired to 1 ohm but are not 1 ohm stable, they are 2 ohm stable at best.
I don't get the "at best" comment. I have never ran into a Kenwood or Alpine that says it'll produce X power @ X impedance that it hasn't done or exceeded.