Quoted from roar:

I’ve considered upgrading speakers in the past but have never gotten my head around paying the price people ask for them. Ultimately I’ve been happy with stock speakers in all my games. I've got a Deadpool LE now and think it sounds fine at the volumes I play at. In comparison over the last couple of years I've had a JP Pro, IMDN Prem, GOT Pro, MET Pro, TWD Pro and some others through the house and I felt they all sounded fine too. If it takes two games side-by-side for you to hear the difference then I wouldn't bother.
I think I get it more from a cosmetic perspective as opposed to a sound perspective. With that all said, there are no shortage of people with better hearing than me or are better tuned in to quality sound, but for my dollars, I'd save them at put the money somewhere else. If you "care" about sound and have found yourself commenting to yourself about the poor sound quality of Stern games then I think it makes sense to upgrade... if you're just looking to buy more stuff for your game for the sake of buying more stuff, go for it.