How to boost bass in headphones?

Do these headphones have good quality and bass?

• Sennheiser dt 770 or dt 990 which one has better noise canceling, bass, sound quality comfort and so no one near me can hear what Im listening too and do they need an amp? (p.s. they're both lowest ohm versions) do I need an amp or could use one if I wanted to boost their bass? So if anyone can recommend any headphones improvement amps to that would e good for 15-30 dollars no other headphone suggestions please, thanks!

• Answer:

  Ignore the first person they don't know what there talking about except for the headphones being beyerdynamic not sennheiser part.The dt770 is closed back while the dt990 is open(there's nothing keeping sound in or out) so that means the dt770 has better sound isolation(noise canceling sort of).The dt770 has the most bass and is fun sounding where the dt990 is moreneutrall.As for the amp part your going to need to stretch your budget to the fiio e11($65) due to both headphones being a tad power hungry.