We are now going to make an experiment of a BTL (balanced transformerless amplifier, not bacon, tomato and lettuce), using two op amplifiers. The BTL is made up of two SEPPs linked with a pushpull. It increases the speaker output by four times.
The signal source is a phase-shifting CR oscillator. The BTL uses two ICs, U1:A serving as a non-inverting amplifier and U1:B as an inverting amplifier.
When you finish wiring the project, turn power ON, press S1 and see (listen?) what happens. You'll hear a high-pitched beep from the speaker. You must have noticed you can't make a loud sound in this experiment, and that's because the power of the two ICs is small.
BTLs actually used in various electronic devices have a transistor operating as a "driver" to increase the output of the two ICs.