My audi has never worked properly!

I made mistake by buying inspiron 3647, sound was awful from day one.  Dell   has spent 20 -30 hours troubleshooting and knows nothing about Maxx Audio (packaged with the computer) or Realtek audio ( also part of preinstalled package)  They disable Maxx audio and the sound still stinks .. I use 2 different pair of Senheiser over ear headphones. AKG over ear headphones .Roland headphones.  The better the headphone the worse the sound  HELP