What chip is used in the Stellar Labs?
The thing with tripath chips is that their supply ratings are typically about 12V-13.2V and comes with a maximum Vs of 14.5V.
Those regulated power supplies sold in hardware stores and in Raon are set to output a standard 13.8V. Technically, this already exceeds the typical 13.2V but since you are still within 14.5V then you may or sometimes may not get away with it.
Those unregulated power supplies, also sold in hardware stores and in Raon can have a no-load voltage output of 16V, not a very good proposition but still, some gets away with using these.
Some will argue with this, I won't. But what I said above is a reality and breaching this settings is almost always the cause for premature failure of these little amps. What you need is either get a linear or smps power supply that has a no-load output voltage of 12V to be within the safe operating area of the chip. There are 12V smps supplies in sulit that you can adjust to exactly get 12V, all you need is a DC plug with wire and an AC main plug. This may be daunting for inexperienced tweakers so I think your option to order a decent 12V wallwart is a much wiser thought.
Cheers