KECES S300+ Power Amplifier

The KECES S300+ is a compact, powerful stereo power amplifier in high-bias Class A/AB technology – the first watts run in pure Class A, above that the more efficient Class AB takes over.

Behind the slender format is a dual-mono build with a massive power supply. Supplied as a single unit – selectable as stereo, bi-amp, or bridged as mono.

Why the KECES S300+?

Because it combines power with control. A 1.2 kVA toroidal transformer with separate windings per channel and 65,600 µF of Rubycon filter capacitance deliver stable energy even on bass transients; up to 45 A peak current per channel keeps the amplifier on course even at impedance dips below 2 Ω. A JFET input and MOSFET drivers give it a smooth character.

What you hear

Control and fine detail: the first 5 watts in pure Class A reveal the finest nuances, and the high damping factor keeps difficult speakers on a short leash. The direct-coupled signal path (no capacitors/coils in the way) keeps the signal pure.

Who is the S300+ suited for – and who isn't it for?

Plain talk: the S300+ is an honest workhorse with no light show – if you want blinking LED chains, look elsewhere. In high-bias operation it runs warm and doesn't belong in a closed cabinet without airflow. If you have a preamp and want controlled power (including for inefficient speakers), you're in exactly the right place.

Can I use the S300+ as a monoblock later?

Yes. Bridged, it delivers 1× 410 W at 8 Ω – so you can expand a pair into a mono power amp combination.

Our verdict

A lot of power amp in a small footprint: powerful, controlled, cleanly built – with Class A finesse at low levels. At HD Zürisee in Wädenswil, we advise you on the right speaker combination.

Awarded: the "5 Hearts Award" from the British trade press (Hifi Pig, 2024) – praised for the effortless power and control reserves with which it lets suitable speakers bloom.

Technical Data – KECES S300+

• Type: stereo power amplifier, high-bias Class A/AB (dual mono)
• Continuous power: 2× 130 W / 8 Ω · 2× 225 W / 4 Ω
• Peak power: 2× 240 W / 8 Ω · 2× 300 W / 4 Ω
• Bridged mode (mono): 1× 410 W / 8 Ω
• Peak current: 45 A per channel
• Power supply: 1.2 kVA toroidal transformer, 65,600 µF Rubycon; separate power supplies for input, driver, output
• Topology: JFET input, MOSFET drivers, direct-coupled
• Modes: stereo, bi-amp, bridged (mono)
• Connections: Neutrik XLR (locking), gold-plated RCA, 5-way binding posts; 12 V trigger
• Protection: DC servo, overload, over-temperature and inrush current protection
• Dimensions (W×D×H): 300 × 279 × 133 mm
• Weight: 14 kg
• Included: S300+, mains cable, manual

Frequently Asked Questions

What does "high-bias Class A/AB" mean in practice?

At low levels the amplifier works like a pure Class A amp (very clean, warm); only at higher levels does it switch to the more efficient Class AB operation.

Does the S300+ also drive difficult speakers?

Yes – thanks to the 1.2 kVA transformer, high damping factor and 45 A peak current, it stays stable even at low impedance. We work out the right combination with you.

Why buy the KECES S300+ from HD Zürisee?

Because a power amp lives off the preamp and speakers. We advise you on the combination and deliver with our own technician – in Wädenswil. Free shipping from CHF 190.

Goes well with

A matching preamp (e.g. the KECES S3 as pre), more power amplifiers and good cables.