1. Einleitung
This manual provides detailed instructions for the setup, operation, and maintenance of your SMSL AS400 Power Amplifier. Please read this manual thoroughly before using the product to ensure proper functionality and to maximize your audio experience.

Figure 1: SMSL AS400 Power Amplifier (Silver)

Figure 2: SMSL AS400 highlighting its functions as DAC, Power Amp, and Headphone Amp.
2. Sicherheitshinweise
- Installieren Sie dieses Gerät an einem gut belüfteten, kühlen, trockenen und sauberen Ort, fern von direkter Sonneneinstrahlung, Wärmequellen, Vibrationen, Staub, Feuchtigkeit oder Kälte.
- Benutzen Sie nur die Lautstärketage specified for this unit. Using this unit with a higher voltage than specified is dangerous and may cause fire, damage to this unit, or personal injury. The manufacturer is not responsible for any damage resulting from the use of this unit with a voltage anders als angegeben.
- Do not attempt to modify or repair this unit yourself. Contact a salesperson or customer service if any service is needed. The cabinet should never be opened for any reason.
- When not planning to use this unit for long periods (e.g., during vacation), disconnect the power cable from the AC wall outlet.
- Die in diesem Handbuch erwähnten Produktspezifikationen und Informationen dienen nur als Referenz. Der Inhalt dieses Handbuchs kann ohne Vorankündigung geändert werden.
3. Funktionen
- Features German Infineon's new digital high-power amplifier chip MA5332MS for high quality, efficiency, and low energy consumption.
- Incorporates Japan's JRC electronic volume control chip NJW1194A for accurate volume control and ultra-low distortion.
- Built-in HDMI (ARC) interface for seamless TV audio integration.
- Supports MQA decoding and MQA-CD playback.
- Equipped with the new third-generation XMOS XU-316, supporting PCM up to 32bit/768kHz and DSD up to DSD256.
- High-end DAC chip CS43131 from Cirrus Logic (USA) for superior sound conversion.
- Eingebauter rauscharmer MM-Vinyl-Phono ampschwerer.
- Latest Bluetooth support for LDAC, APTX/HD, SBC, AAC codecs.
- All-aluminum alloy CNC precision-processed shell with anodizing technology and chamfering for exquisite workmanship.
- User-friendly operating system with full-function remote control.
- High-quality gold-plated input and output terminals.
- Includes perfect overheating and overcurrent protection circuits.
- Built-in high-quality, high-power audio special switching power supply.

Figure 3: Key audio components including Infineon MA5332MS amplifier, Cirrus Logic CS43131 DAC, and XMOS XU-316 USB interface.
4. Display Interface and Controls

Abbildung 4: Vorder- und Rückseiteview of the AS400.
Vorderseite
- Funktionsknopf: Press to enter the menu; Hold to exit the menu; Rotate to change the value or volume.
- 4.4-mm-Kopfhörerbuchse
- 6.35-mm-Kopfhörerbuchse
- Remote-Fenster
- Anzeigebildschirm
Rückseite
- PHONO-Eingang: For connecting turntables.
- LINE-Eingang: Standardmäßiger analoger Audioeingang.
- Koaxialer Eingang: Digitaler Audioeingang.
- HDMI(ARC) Input: For TV audio return channel.
- Bluetooth-Antenne: For wireless audio reception.
- AC Power Input (100-240V AC)
- Erdungsklemme
- SW Out (Preamp): Subwoofer pre-out.
- USB Input (PRE): USB-Audioeingang.
- Optischer Eingang: Digitaler Audioeingang.
- Rechter Kanalausgang: Speaker terminal.
- Ausgang des linken Kanals: Speaker terminal.
5. Fernbedienung
The AS400 comes with a full-function remote control for convenient operation. Ensure batteries are installed correctly (2 x R03/AAA batteries).

Abbildung 5: Aufbau und Funktionen der Fernbedienung.
Fernbedienungsfunktionen:
- Ein-/Ausschalten: Schaltet das Gerät ein oder aus.
- Oben unten: Navigieren Sie durch die Menüoptionen oder passen Sie die Einstellungen an.
- MENU/OK: Ruft das Menü auf oder bestätigt die Auswahl.
- Zurückkehren: Kehrt zum vorherigen Menü zurück.
- Eingangsauswahl: Cycles through available inputs.
- Stumm: Schaltet den Ton stumm oder hebt die Stummschaltung auf.
- Ausgangsumschaltung: Switches between speaker and headphone outputs.
- Lautstärke +/-: Regelt die Lautstärke.
Batterie Informationen:
- If the remote control is ineffective when close to the unit, replace the batteries.
- Wenn die Fernbedienung längere Zeit nicht verwendet wird, nehmen Sie die Batterien heraus.
- Entsorgen Sie gebrauchte Batterien gemäß den örtlichen Vorschriften.
6. Einrichtung und Anschlüsse
6.1. HDMI-ARC-Anschluss
Connect your TV's HDMI ARC port to the AS400's HDMI(ARC) input using a compatible HDMI cable.

Figure 6: Diagram for connecting TV via HDMI ARC to the AS400.
- Connect to an HDMI IN port labeled "ARC" or "eARC/ARC" on your TV. If connected to a port that does not support ARC, the ARC input function of this product cannot be used.
- Use an HDMI cable (19 pin) with the HDMI logo indicating compatibility with ARC. You may need to adjust TV settings; refer to your TV's user manual.
- This product supports digital audio input via HDMI ARC, but it cannot output video.
- If your TV does not support ARC, connect the TV's audio output (OPTICAL, COAXIAL, or AUX) to the corresponding input on the AS400.
Video 1: Demonstrates how to connect the SMSL AS400 using HDMI ARC and provides important tips for setup.
6.2. Phono Input
Connect your turntable to the dedicated PHONO input on the rear panel. Ensure proper grounding for optimal sound quality.

Figure 7: Connecting a turntable to the built-in low-noise MM phono preampschwerer.
6.3. Bluetooth-Eingang
Pair your Bluetooth-enabled device with the AS400 to stream audio wirelessly.

Figure 8: Bluetooth input setup, supporting LDAC, APTX/HD, SBC, AAC.
Bluetooth-Pairing:
- Open Bluetooth pairing on your mobile phone, search for and select "SMSL AS400".
- If your phone displays "Connected", pairing is successful.
- If pairing fails, use the Bluetooth clear function on the AS400 to clear previously connected devices, then retry.
6.4. Speaker and Headphone Outputs
Connect passive speakers to the speaker terminals on the rear panel. Use the 4.4mm or 6.35mm jacks on the front for headphones.

Abbildung 9: Bspample of a 2.1 channel system setup with the AS400 and a subwoofer.
- Lautsprecheranschluss: Pay attention to polarity (+ and -) when connecting speakers to ensure correct sound quality.
- Kopfhöreranschluss: The AS400 features both 4.4mm (balanced) and 6.35mm (unbalanced) headphone outputs.

Figure 10: Dual headphone jack design for diverse headphone compatibility.
7. Bedienung
Video 2: Ein umfassender Überblickview of the SMSL AS400's user interface, settings, and various functions.
7.1. Menünavigation
Use the function knob on the front panel or the remote control to navigate the menu:
- Knopf drücken: Menü aufrufen.
- Hold Knob: Menü verlassen.
- Drehknopf: Change values or volume.
7.2. Input and Output Settings
The AS400 supports various input and output options, selectable via the menu:
- Eingabeeinstellungen: USB audio, Optical, Coaxial, Bluetooth, ARC IN, AUX IN, PHONO.
- Ausgabeeinstellungen: Speakers, Headphones.
7.3. EQ and Tone Controls
Customize your sound with various EQ presets and tone adjustments.
- EQ-Modi: Direct, Tone, SDB, Bass, Super Bass, Rock, Soft, Clear.
- Bass-Einstellbereich: -9dB to +9dB. (Changing Bass in Direct or other EQ modes will switch to Tone mode).
- Höhen-Einstellbereich: -9dB to +9dB. (Changing Treble in Direct or other EQ modes will switch to Tone mode).
7.4. Digital Filters
Select from various digital filters to fine-tune the audio characteristics:
- Schneller Filter mit geringer Latenz
- Schneller und phasenkompensierter Filter
- Langsamer Filter mit geringer Latenz
- Langsamer und phasenkompensierter Filter
- NonoversampLing-Filter
7.5. Farbeinstellungen anzeigen
Personalize the display screen color:
- White, Red, Green, Blue, Yellow, Cyan, Orange, Purple.
7.6. MQA-Wiedergabe
The AS400 supports MQA decoding via USB, optical, and coaxial inputs.
- No special playback software is required for MQA playback. For optimal quality, set your computer's audio output to ASIO or WASAPI and adjust the computer volume to maximum.
- Beim Spielen von MQA files, the display will show the sampling rate of the original master recording.
7.7. MQA-CD Playback
- Ensure the MQA-CD is genuine.
- Verify that the optical or coaxial signal output of your CD player is an unprocessed source code.
7.8. Dimmer Settings
Adjust the display brightness behavior:
- Immer auf: Display remains on.
- Auto aus: Das Display schaltet sich nach 5 Sekunden Inaktivität automatisch aus.
7.9. Stellen Sie die Werkseinstellungen wieder her
- For Bluetooth Input: Press and hold the middle button of the knob to reset only the Bluetooth pairing status.
- For Other Inputs: Press and hold the middle button of the knob to erase all settings, including Bluetooth.
8. Troubleshooting (HDMI ARC Function)
Here are some common questions and answers regarding HDMI ARC functionality:
- Q1: The ARC input is connected to the TV, but the TV does not recognize the device or produce sound?
A1: The ARC input needs to be connected to the HDMI ARC interface of the TV, and the output mode of the TV should be set to "ARC/ARC+TV speakers". - Q2: Can the TV remote control adjust the volume of this product?
A2: Nicht unterstützt. - Q3: Will the product synchronize on/off after turning on/off the TV?
A3: Not supported. When using HDMI ARC input, this product needs to be restarted when the TV is turned off and then turned on again. - Q4: What should I do if there is no sound after connecting the TV to the product?
A4: When using this product, please confirm that the audio output format of the TV is PCM. - Q5: Does it support connecting to a TV set-top box?
A5: Nicht unterstützt.
9. Spezifikationen

Figure 11: Detailed technical specifications and dimensions of the AS400.
| Parameter | Wert |
|---|---|
| Eingänge | RCA / BT / USB / Optisch / Koaxial / Phono / I2S |
| Klirrfaktor | 0.003 % |
| SNR | 107 dB |
| Ausgangsleistung (RMS) | Stereo 4Ω: 165Wx2, 8Ω: 85Wx2 |
| Kanaltrennung | 98 dB |
| Eingangsempfindlichkeit/Impedanz | 280 mV/22 kΩ |
| USB-Übertragung | Asynchrone Übertragung |
| USB-Kompatibilität | Windows 7/8/8.1/10/11, Mac OSX, Linux |
| MQA-Decoder | USB / Optisch / Koaxial |
| MQA-CD-Decoder | Optisch / Koaxial |
| Bittiefe (USB) | 1 Bit, 16–32 Bit |
| Bittiefe (optisch/koaxial) | 1 Bit, 16–32 Bit |
| Samplange Datenrate (USB PCM) | 44.1 ~ 768 kHz |
| Samplange Rate (USB DSD) | 2.8224–11.2896 MHz |
| Samplange Rate (optisches/koaxiales PCM) | 44.1 ~ 192 kHz |
| SampDatenrate (optisch/koaxial DSD) | DSD64 (DoP) |
| Energieaufnahme | 40 W (Normale Lautstärke) |
| Größe (BxHxT) | 210.4 x 46 x 254M (8.28 x 1.81 x 10 Zoll) |
| Gewicht | 1.568 kg (3.46 Pfund) |
Note: SMSL reserves the right to make improvements which may result in specification or feature changes without notice.
10. Garantie und Support
10.1. Garantiebedingungen
- Foshan Shuangmusanlin Technology Co., Ltd. offers good-quality products. If the product breaks within 7 days of purchase under normal use, you may choose a return, replacement, or repair (provided the product does not affect resale). Free repair is provided for one year under normal use.
- The purchase date is determined by the invoice or receipt from the seller. For online purchases, a screenshot of the transaction can serve as proof.
- The warranty will be void if the unit is damaged due to inappropriate usage, including:
- Damage from use in non-normal working environments or not following instructions.
- Dismantling, refitting, or repairing by the user.
- Damage caused by using non-designated or non-accredited fittings.
- Inability to provide credible proof of purchase.
- For returns or replacements, please send the product back to your S.M.S.L audio reseller.
10.2. Kundendienst
For any questions or support needs, please contact your S.M.S.L audio reseller. The manufacturer, LIN.LIN.LIN, is committed to providing reliable products and customer service.

Figure 12: Customer support details for LIN.LIN.LIN AUDIO, the brand behind SMSL.