A 3.5 mm AUX port on a digital only output device would need a DAC , thought I usualy only see a 3.5 mm headphone jack on those devices, rarely a 3.5 mm AUX port). Analogue capable devices sometimes had two 3.5 mm ports for ages, one for headphones using an internal amplifier (often pretty bad)and one to plug directly into an amplifier called the 3.5mm AUX. Sound wasn’t preamplified before the 3.5 mm AUX plug. That caused many people to confuse 3.5 mm AUX and 3.5 mm headphone jacks and wonder why the sound was barely within hearing range. I beleive OP got confused in the nomenclature.