Are coupling capacitors always needed at the input stage of a power amp?

And usually, how is there value chosen?

Zc = 1/jwC == |Zc| = 1/wC

Lets take 30 Hz as our low frequency, then |Zc| = 1/2*pi*30*C

Ok, then we get a value |Zc| = 1/kC
What determines the value of C? Is it the input impedance of the amplifier?

Thanks

descrete pow amps do . I dont do descrete for noise .

, but integrated nix caps , everything is DC cause
inside it's easy to keep DC balance .

BTW Never use cross overs , Use "Bi-Amping" .
1 amp for tweeters ( gas built in Hi pass filter , 1 stereo amp for
woofers
(Has a bult in Low pass )

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Lost'n Found wrote:
Are coupling capacitors always needed at the input stage of a power amp?

And usually, how is there value chosen?

Zc = 1/jwC == |Zc| = 1/wC

Lets take 30 Hz as our low frequency, then |Zc| = 1/2*pi*30*C

Ok, then we get a value |Zc| = 1/kC
What determines the value of C? Is it the input impedance of the amplifier?

Thanks