I think what rgd1101 is correct, It will check for correct hardware first.
Now, back to finding the driver, it took me a while to look but there are like "thousand" different dell Inspiron 5xxx models, finding your exact model is not possible with guesswork.
At quick glance, pretty much all of them, even ones advertized to ship with Maxx audio, are using normal realtek sound cards
Your current motherboard (No idea if it's Z270 or X370 though so can't link to the download) has same brand realtek card, downside is, your chip is likely different. You should get equivalent settings by installing the full realtek software suite though.