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That's right , but I would add the phase shift of low pass filter , the lack of noise and probably a sort of imprinting , because we learned to listen to the music with vinyl records ( before 1982 ). See also Bob Carver's Digital time lens . Anyway , fortunately amps and speakers are analog ...

Not only ! Analog sources sound a little better in the mid range ( IMHO of course ). Ciao Marco

And the winner is : Xi Jinping ! The West is in bad shape ! Ciao Marco

just out curisity , who is Amir ? Is the founder of Audio Science Review ( ASR ) forum ? " the man with Pink Panther " ? If yes, he seems like a divisive person to me. Ciao Marco

Welcome aboard ! Marco

Ciao e benvenuto ! Marco

Ciao from Italy ! Marco

Ciao from Italy ! Marco

You must use 0,01 uF 400 V for 120 VAC or 0.022 uF 630 V for 230 VAC .( typical values ) Anyway after replacing the power switch , it's better to use a 16 A relay in series or Don's circuit . I use a 16A relay on PL 4000 ( with capacitor ) to power PL 700B on . and an external power strip with...

Exactly like that . Ciao Marco

O.K. But there are other brands ! PL is a must , but I have also Marantz , Dynaco , Yamaha and Quad . They sound different but they sound great ! Ciao Marco

A mistake ,sorry : not with 400 . Ciao Marco

I mean the relay on PL 4000 for switched AC outlets . On service manual rev . 6 81 it's written : Note : the relay is not capable of switching power amplifiers rated at greater than 250W / channel. In other words : PL 400 yes and PL 700 no . Infact I had problems with 700 and not with 700...

I restored 2 PL 4000 units , so I would add some other considerations : - mother board and front board are critical below S/N 2000 - caps values are critical (35 V in stead 63 V ) below S/N 5000 - RCA connectors are really a disaster ( they are too fragile after 45 / 50 years ) -Output relay...

Correct but it's too close to the limits . Ciao Marco P.S: I am very conservative

O.K. LME 49860 specs says : Easily drives 600 Ohm loads and Output short circuit protection . If you use this Op Amp I agree with you . I' m not sure that OPA 2134 is able to drive "easily a 600 Ohm load " and it has a good short protection . Ciao Marco

An OP amp is " the same " as a signal transistor for the power . https://sound-au.com/project24.htm This is only an example . Anyway prepare a cable RCA / jack and test , but for me the output power of an op amp is not sufficient also with a 600 Ohm load . Ciao Marco

If you use the PL 4000 front jack output with a 600 Ohm headphone ( tested with HD 414 ) the signal is too low , because there two 1,2 kOhm resistors in series . The reason is to protect the two output transistors ; this output was intended as "aux" . According the service manual rev. 6-81...

I was simply considering a stock PL 2000 preamp . Sorry for mismatch . Ciao Marco

Marantz 3200 preamp has no internal headphone amp ; it uses the power amp connected to output jack via 2/3 W resistors . Generally headphone amps use medium power transistors ( BD 139 / 140 ) , but I think you need to redesign the PSU . You could copy the C4000 schematic . Ciao Marco