I think it depends on what type of device you are powering. If it is an audio component such as a DAC or TT motor, it would be wise to replace the wall-wart with a better PSU, which includes the transformer and better power cable.
For a laptop or tablet running a digital library, an AC wall adapter might be fine due to portability reasons. Although, battery power would most likely provide better SQ for audio files.
Some AC adapters convert AC from the wall to DC for the device, some pass AC thru the transformer to the device. As stated above, the thin gauge wire provided is based on the current draw of the device.
For a laptop or tablet running a digital library, an AC wall adapter might be fine due to portability reasons. Although, battery power would most likely provide better SQ for audio files.
Some AC adapters convert AC from the wall to DC for the device, some pass AC thru the transformer to the device. As stated above, the thin gauge wire provided is based on the current draw of the device.