10 watts would be 'loud' from that distance, you're not getting 10 watts out, which begs the question what is the impedance of the speakers you have attached to the amplifier? The TDA2003 is only rated at 10 watts with a 2ohm load, which means automotive type or otherwise very low resistance speakers. If you're connect this to common household speakers which are often 8-16 ohms the only way to increase performance is to put more speakers in parallel.
Pictures of the speakers you're using might help as well, but impedance is most important.