Stress on Solid State Amps

If the amp was never stressed then you are stuck waiting for it to break/burn in. Unless you are planning to camp out in an igloo and subject it to dramatic temperature swings it is difficult to over stress it under normal household conditions.

Creating power requires heat dissipation and modern electronics are designed with high temperatures in mind. Dependable is a manufacturer trait and unless someone has totally swamped the amp with high loads or bridged it to beyond specification normal use shouldn't affect its life span.

In fact, the Wadia 27 DAC runs so hot, as it was designed, one can make breakfast on it.

I also have for sale a 69 Hemi Charger that my grandmother only drove to church on Sundays and has never been stressed.

An amp is "stressed" much more by turning it on from a cold start than by playing it full volume for weeks on end. An amp driven to clipping occasionally or if played at higher power settings is more dependable than an amp that has been sitting idle for years - but not less dependable than one that's been coddled. Things like humidity, temperature extremes, cigarette smoke, pet dander, electrical surges and the like will have a far greater impact on life expectancy than just by simply playing it loud or often. No one will mention those stress items in their ads too frequently...

Class A amps will run much cooler at full power than at idle or low power so amplifier class should be taken into consideration.