Some motherboards have software that allows you to change the soundcard settings which would in turn make your headsets sound louder and by comparison, make them sound like they have more bass and treble. My V Rampage 10 motherboard has settings for the motherboard to change the sounds, which you can make things sound softer and then there is a setting that allows you to increase the volume the soundcard outputs. The AWP on CS:GO with the motherboard setting to make things louder, sounds like legit thunder in both loudness and by comparison bass. It's ridiculous honestly but not something I would use for long because it makes EVERY sound louder. Have a kid screeching in your game? Forget about it, your hearing is gone lol
Headsets aren't known for their sound quality. Some headsets will sound louder than others or have better bass and/or treble than others, but overall, the lack of sound quality is something people will have to settle with, for the ease of access to a mic built in. There's plenty of $50-$70 headphones that can beat $200 headsets in terms of sound quality, because headphones only have to focus on sound, instead of sound and a mic. Sennheiser is known for their sound quality; however, that doesn't mean they will be strong suited in just one area such as bass. There are headsets out there that are bass heavy, but very bad quality in sound, sound is not clear at all and in some cases will be heavily distorted. Then there are headsets out there that are crystal clear sound, yet have no bass to them at all, almost as if all sound is at the audio level of a parent reading a bedtime story to their kid. Then of course you get the mixed quality where it's either a 50/50 split in terms of sound to bass, some will be a little more bass heavy while still giving decent sound or some will be clearer in sound but a little weaker on bass.