Locate the audio tone control or equalizer. Maybe a bad transmission of the lower frequencies due solely to their misconfiguration. Increasing the bass level, don't forget to at least partially suppress high. The sound quality will be much nicer without any alteration of the equipment. But remember that too strong a blockage of high frequencies not everyone likes.
In the absence of not only the equalizer, but even a regular tone control, add it yourself. Connect between the output of the signal source and the amplifier input resistor of about 1 kOhm. Then take a capacitor of about 0.1 UF and switch it between the amplifier input and ground through a variable resistor about 20 kω. Using this simple device, you can adjust the timbre of the sound.
Try to find an audio switch dynamic bass boost. Turn it on. But try not to use this mode with headphones, because the specific techniques used in dynamic bass boost, according to some, is not harmless to the ear.
Try changing speaker system to a higher quality. You will find that the bass performance will be significantly improved even when using the same amplifier. But avoid using subwoofers with separate power amplifiers. Subwoofers are able to develop at low frequencies such a large sound pressure that is necessary to speak about danger not so much for hearing as internal organs.
Remember neglected in our days acoustic systems, so-called open type. This column, by design, able to efficiently reproduce low frequencies only in the case if it is oversized. However, it sounds nicer and, more importantly, a good "shake" it can power even a few watts because it has a high efficiency. Oddly enough, the best sound at times single-band speakers, where the center is located a huge box of modest dimensions dynamic head. The health risks inherent in the subwoofer, outdoor speakers absent, although to the ear the bass is not very good. Unlike usual, this speaker system can be made independently, and the knowledge and skills required, rather, the field of electronics, and from the area of carpentry skill.
And the last one. If you are using the dynamic driver without a box, place it in such. You will be pleasantly surprised to find that the same head sounded a completely new way.