Here's a nickle tour of what I learned about digital music. Two things primarily impact sound quality of digital recordings - bit depth and sampling frequency. Sampling frequency is how often the system takes a "sample" of the digital data. From what I can figure, this is similar to "frames per second (FPS)" in a motion picture. The more FPS the smoother more seamless the picture (think about the old flip-books of a galloping horse vs the old B&W silent movies vs todays movies). Similar for music, the higher the sampling rate, the less chance for rough music. I'm sure this ties in with buffering somehow but that's more technical than I care to get. But most digital music systems these days operate at 44kHz. There are higher frequency systems but what I read is they mostly capture higher sound frequencies we humans can't hear anyway. So there is a diminishing return to pay for a higher frequency system.
Bit depth is best defined as the number of bits per sample. Most common bit rates are 16, 24, and 32 bits. It's pretty easy to find 32 bit systems so that's doable. But bit rates depend on processing capacity, so the higher the bit rate, the more powerful the processor, and the more it costs. The player (processor) produces the signal based on sampling rate and bit depth that goes to your speaker.
So the next piece of the puzzle is the speaker. A cheapo speaker (or ear buds) will convert high end digital data to hollow, tinny sounding noise. Conversely, a high end speaker can't convert a cheapo digital signal into good sound. In a wood shop or job site, where one is typically surrounded by load noise, it might not make sense to buy high end equipment for sound quality. Might make more sense to buy rugged, durable equipment that can stand dust, noise, the possible drop or knock, etc. For less hazardous environments, it makes sense to consider the best sound quality you can afford balanced with battery life, ability to play multiple data formats (e.g. MP3, WAV, FLAC, whatever your music is saved in - some players I saw only handled certain formats which would require one to convert other formats), storage capacity, transportability, and ease of uploading songs, making playlists, etc. If you're playing this through the speakers in your truck, if those aren't decent speakers, you can waste money buying a high end player. The music will only be as good as the weakest part of the system.
I get a kick out of ads for TV's that try to show you how clear the picture is - and the person looking at the ad is looking at it on a cheapo laptop with low resolution.