The SMSL PA400 is a Class D stereo power amplifier built on Infineon GaN transistors switching at up to 1MHz, rated 250W x 2 into 4Ω and 500W into 8Ω in XLR mono (bridged) mode, with TI PGA2311 volume control and a remote. It suits listeners driving passive speakers from a DAC or preamp.
Who the SMSL PA400 is for
Passive speaker systems: Rated 250W x 2 into 4Ω, with a menu setting that matches the amp to 4Ω or 8Ω speakers.
DAC-direct setups: The TI PGA2311 volume stage and RC-8A remote let a fixed-output DAC connect straight to the XLR or RCA input.
Preamp owners: A stereo pure-amplifier pass-through mode is built in for systems where an external preamp sets the volume.
Mono-block upgrades: In XLR mono mode, two PA400s form a stereo pair, each rated 500W into 8Ω.
Skip it if: You want a one-box system: the PA400 takes analog XLR and RCA signals only, with no built-in DAC, Bluetooth or headphone output.
SMSL PA400 key specs
Amplifier: Class D with Infineon GaN FETs, switching at up to 1MHz
Output power (stereo): 250W x 2 @ 4Ω
Output power (mono mode): 500W x 1 @ 8Ω (XLR mono input)
SNR / channel separation: 115dB / 75dB
Inputs: XLR balanced, RCA line, mono XLR
Input sensitivity: RCA 0.96Vrms; XLR 2.1Vrms (2.7Vrms in mono); 22kΩ
Volume and control: TI PGA2311 volume chip; front display and knob; RC-8A remote (2 x AAA)
Power: Built-in supply, 100–240V AC; standby under 0.5W
Size and weight: 254 × 47.7 × 242mm (W × H × D); 2.58kg (5.69lb)
Color: Silver
Genuine SMSL stock. Free shipping on every order, 45-day returns.
SMSL PA400 vs similar options
vs SMSL PA-X: Shares the PA400's Infineon GaN stage, PGA2311 volume, 250W x 2 @ 4Ω and 500W mono ratings in a 222.5 × 51 × 250mm case; pick the PA400 for its lower, shallower 254 × 47.7 × 242mm chassis.
vs SMSL VMV A1 Pro: A black GaN power amp from SMSL's VMV flagship line, built as the power stage of a two-box speaker system; pick the PA400 for 250W x 2 @ 4Ω and stereo XLR inputs in a silver chassis.
Yes. Every unit we sell is genuine and brand-new, shipped in its original packaging, and backed by our 1-year TonePier warranty and 45-day returns.
Where does my order ship from, and how long does it take?
Every order ships from our warehouse in China, with full tracking, and most orders ship within 3 business days. Shipping is free on every order; most US orders arrive within 7–15 business days and most orders to other countries within 7–20 business days — see our shipping policy for details.
What if it isn't for me?
You get 45 days to decide. Keep the packaging, keep it in like-new condition, and send it back for a refund. Ear tips unsealed for hygiene reasons are fine — we expect you to actually listen.
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