Keywords: TR509, swimming earphone, no bass, weak bass, bad sound
These are designed for active people to listen to music while doing activities, NOT audiophile In-Ear-Monitors designed for critical listening of Hi-Res FLAC files on a Dragon-fly or other high-end DAC.
These earbuds have a well-balanced sound with sufficiently adequate bass and highs that are not fatiguing. The amount of bass can vary depending on the ear tips chosen and whether the earbuds are properly seated in your ears.
If you really mind this point, please contact firstname.lastname@example.org for help.