04-11-14: Atmasphere'Stable' means that the amp won't oscillate when presented with the load in question.
Stable is a given with any amp, you may have missed the rest of the Martin Logan quote for the type of amp they recommend for their speakers. And to get these sort of figures, the amps need low output impedance, to get it. So here it is again.
" Be able to deliver NEARLY twice its rated 8 Ohm wattage into 4 Ohms, and should again increase into 2 Ohms."
In other words for the uninitiated, what's needed is an amp that can ALMOST double it's 8ohm wattage for each halving of load.
EG:
8ohm-100watts
4ohm-200watts
2ohm-400watts
Cheers George