This is the OEM manufacturer service manual with all the info, schematics/schematic diagrams, etc.
eBay
Line Magnetic Tube Amplifier Analog Sound 805 A Integrated Dual Channel Power Amplifier
Aliexpress UK
Es ist gut, wenn man dort nachsehen kann, wie herum der Kondensator nun eingebaut war, den man gerade zwischen den Fingern hält, um den Neuen wieder richtig herum einbauen zu können (vereinzelt kann man auch Platinen-Aufdrucken nicht trauen, sofern vorhanden).
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2 Channel PA/DJ Power Amplifier 1U Lightweight Amplifier 8 Ohm 200W 4 Ohm 350W Suitable for Performance Conference Hall Karaoke
Aliexpress UK
Model: 2240PE. NAD Service Manual.
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WOOPKER ZK-MT21 Sound Amplifier Module 2x50W+100W 2.1 Channel Subwoofer Bluetooth 5.0 Digital Power Amplifier Board AUX 12V/24V
Aliexpress UK
A good idea is to replace all the electrolytic capacitors with new ones. They also have a low ESR. You can also get the factory service manual to the NAD C316BEE as an addition. I will send it in PDF format.
eBay
300W bluetooth Digital Power Amplifier Board 220V/50Hz EU Plug Home karaoke TF card / U disk MP3 Player Subwoofer Amplifier
Aliexpress UK
A good idea is to replace all the electrolytic capacitors with new ones. They also have a low ESR. You can also get the factory service manual to the NAD 120 as an addition. I will send it in PDF format.
eBay
IRS2092S HiFi 500W Mono Digital Power Amplifier – Class D Audio Amp Board for Home Theater & Pro Audio
Aliexpress UK
A good idea is to replace all electrolytic capacitors with new ones. They also have a low VES. You can also get the factory service manual at NAD 3020B as an addition. I will send it in PDF format.
eBay
AK-170 Mini HiFi Audio Amplifier 200W+200W 2-CH Power Amp with RCA Input
Aliexpress UK
I send the one u see thank you
eBay
4-Channel Car Amplifier (60Wx4) 240W Max Power for Large Display Android Devices Audio Subwoofers and Speakers Car Stereo AMP
Aliexpress UK
A good idea is to replace all the electrolytic capacitors with new ones. They also have a low ESR. You can also get the factory service manual to the NAD 701 as an addition. I will send it in PDF format.
eBay
4 Channels Mini o Stereo Headphone Amplifier HA400 Ultra-Compact Audio Amplifier With Power Adapter EU US Plug Adapter
Aliexpress UK