Clueless got it right...we are talking about interstage coupling capacitors being eliminated. A Direct coupled amp has response down to DC: which means that if you put a constant 1 volt on the input you will get a constant 25 volts (or so) at the output.
The idea of a using a direct coupled amp for music is not entirely logical, since the music only goes down to 20 Hz or so. Coupling capacitors large enough to pass 10 Hz or so should suffice. However, there is a certain elegance in following the input signal precisely, even down to dc, and some amps made this way sound good, although that might be for different reasons.
A dc coupled audio amp is really a controllable dc power supply, such as might be used in an electonics lab. In fact, some years before dc coupled audio amps were marketed one manufacturer of power supplies was demonstrating the high slew rate of his product by playing music through it.
The idea of a using a direct coupled amp for music is not entirely logical, since the music only goes down to 20 Hz or so. Coupling capacitors large enough to pass 10 Hz or so should suffice. However, there is a certain elegance in following the input signal precisely, even down to dc, and some amps made this way sound good, although that might be for different reasons.
A dc coupled audio amp is really a controllable dc power supply, such as might be used in an electonics lab. In fact, some years before dc coupled audio amps were marketed one manufacturer of power supplies was demonstrating the high slew rate of his product by playing music through it.