Look at the datasheet fot the TDA2003 IC. Its minimum supply voltage is 8V then it operates poorly.
Look at the datasheet of a 9V alkaline battery. Its voltage quickly (15 minutes?) drops below 8V when it has a load of about 100mA.
The TDA2003 produces an output power of only 1.3W into a 4 ohm speaker with a brand new 9V battery. Its output into an 8 ohm speaker will be only about 0.7W.
Use a TDA2822 IC instead. It is small, works when its supply voltage drops down to 3V and costs only $1.56US at Digikey today. They have more than 1000 of them in stock.
Its output to an 8 ohm speaker is 2.6W with a brand new 9V battery.
Its idle current is 6 times less than the high idle current of the TDA2003.
A pcb design is in its datasheet. Somebody might make a kit with it.