Would a desktop PC soundcard be decent enough?
If you are thinking of the soundcard I was talking about earlier, it is completely different from what comes in any typical PC. Typical PC sound uses the main processors to do all the work. All the work!
The sound card I use has its own seperate processors built in and requires a much higher output type of power supply to do what it does.
One of the reasons to go to all that trouble and do all that is to get better, smoother, more refined and stable DC voltage for your sound processors to work from. This will be miles ahead of what ever DC power soup floats along the typical USB buss or even a spare out at the original power supply.
This card is older, but it originally cost more than the PC I used it in. I have since upgraded to an even more advanced sound card for the music server I built for JUST music storage and playback.
The Win 10 computer I am typing on right now uses the older sound card after upgrading my main one. I use this one mainly for transfer of analog (LPs or reel to reel tapes) to digital files in a most convenient way.
I had to refit this computer with about double the power suppy size. It came with 400W PS and I replaced the original with a 950W PS.
Now the original motherboard based sound on this machine, which would be comparable to almost any other pre-built, off the shelf macine sound is adequate for most uses and yes, again the software comes into play.
Since this machine came with a DVD player, it also had some rather advanced options native to using a Home Theater set up with this PC. All that software was a part of the Real-tek built in sound.
Before I could use any of my upgraded sound card's features, I had to go in and clear out all that Real-tek installation stuff, "The Hard Way!"
So a shorter answer might be, "Yes, the PC sound is probably better than the sound from a hand held portable device."
The problem is, like Odeon mentioned, those devices you are connectiong to did not have very good sound to start with.
You can not improve upon or fix what is not already there.
The easier answer still is to plug it in, give it a listen and draw your own conclusions about the quality.
It should be fine for most uses.