It may or may not be possible, but I'd also be concerned that the DC may be too noisy to power an audio amplifier in the speakers. I had been waiting to see if anyone responded that has actually tried this, though.
There was a time when some manufacturers were actually making amplified sound cards. I wish I had one of those to try. I enjoy using 'regular' speakers, so I currently use an old 30 watt Technics integrated amp and some Realistic Minimus 7 speakers.
I do plan on buying a T-Amp that I mention on another recent post, as soon as the sellers get more stock. For ~$35.00, it sounds like a real value and it is tiny.
My long term goal is a portable tabletop jukebox in an attractive case. Kind of like an old suitcase-style record player.
Brian