PS Audio Stellar S300: Audio overachiever

PS Audio’s Stellar range is meant to offer superlative value – and it does. But even without its keen price tag, the Stellar S300 stereo power amp would have been deemed a star performer that can hold its own in top-notch company …


It’s taken more than six months to write review – perhaps more, because I can’t quite remember when the PS Audio Stellar S300 was first delivered for review.

It arrived brand new, and while I decided to purchase the review unit after the first five hours of listening, the amp kept on shifting the sonic goalposts. As the S300 employs a Class D output stage, I never anticipated any extended run-in time – but I was wrong.

I can now confirm that as good as the S300 sounds virtually out of the box, patience is richly rewarded: after well over 300 hours, there have been consistent improvements in overall performance, with low-down bass punch the single biggest beneficiary.


The Stellar range – currently consisting of the Gain Cell pre-amp/DAC (review here), the S300 stereo power amp under scrutiny here, and the M700 monoblock amplifier. The range attempts to offer that most elusive of combinations in hi-fi: affordability and sonic excellence.

The Gain Cell pre-amp/DAC already provided some insight into how successful this PS Audio initiative has been, offering as it does an extensive features list and satisfying sonics at an attractive price point – even when paying in our exchange rate-weakened SA currency.

The S300 is the pre-amp/DAC’s natural partner. It shares similar cosmetics, with identically configured, all-metal casework. The S300’s sturdy design does without the pre/DAC’s controls and display, and what remains is elegantly simple and attractive.

The top and bottom anodised alloy covers (available in black and silver) are curved at the front to form a split front fascia that’s adorned by nothing more than the ubiquitous blue-lit PS Audio logo that is also the power switch.

The sides feature cooling louvered, but the S300 remains only mildly warm, even when driven with gusto. The rear panel is occupied by two sets of stereo binding posts (making life easier for those with individual cable runs for bi-wired speakers), and a choice of either balanced XLR or single-ended RCA inputs.

An IEC power socket is accompanied by a rocker on/off switch, which remains permanently on during normal use. The front power button switches the amp between standby and operational modes. For custom installations, the S300 is equipped with a 12V trigger input/output pair to allow for remote switch-on

The casework sits on simple rubber feet, and more fastidious users may want to upgrade these to something with slightly better isolating properties. That said, the overall impression is of a solidly built, attractive, no-frills piece of kit.


As it turns out, the real attention has been lavished on what matters most: the electronics. The S300 is a hybrid design that combines the acknowledged strengths of Class D amplification – high efficiency, low distortion, high current and absolute linearity – with an innovative input stage that addresses any concern about harshness and clinical tonality that some still associate with Class D tech.

PS Audio calls the in house-designed input stage an Analog Cell. It features a fully differential, zero feedback, discrete Class A circuit employing MOSFETs, and was carefully voiced during hundreds of hours of listening tests.

The Analog Cell concept recognises the need for an efficient, truthful interface between pre-amp and power amp, while allowing the sonic signature to be fine-tuned in order to iron out any tonal anomalies.

The Class D output stage employs a fully balanced, dual-mono design, with each channel benefiting from its own, separate power supply. PS Audio has opted for the Danish ICEpower Class D amplifier modules.

Originally developed for sue by Bang & Olufsen, the ICEpower technology has been extensively developed and improved since the late 1990s, and is now widely adopted by many leading audio brands.

In the case of the S300, power output into 8 ohms exceeds 135 watts per channel, and reaches beyond 300 watts per channel into 4 ohms. The amp is 2 ohm stable, with a frequency response that extends all the way to 50 kHz.


The S300 was first powered up in the AVSA listening room, where it partnered its Stellar stablemate, the Gain Cell pre-amp/DAC in a system that also included a Lumin D1 network player, Primare PRE32/MM30 pre-amp, Parasound Halo A21 power amp, and Vivid Audio B1 Decade loudspeakers.

It was after that initial review and about 25 hours of play-in time that I opted to buy the review unit for use in my home listening room, where it now partners a Naim Uniti2 used in pre-amp only mode, and powers a pair of Vivid Audio Oval V1.5 speakers.

As I mentioned earlier, I delayed compiling the final review several times as the amp seemed to improve steadily over time. With well over 300 hours now under its belt, I think it’s reached a representative level worth recording.

Source material for the review was provided by a PS Audio DirectStream DAC equipped with a Bridge II network interface and running the latest Red Cloud firmware. Roon V1.4 and the recently released V1.5 software was used to manage music selections from either from a Synology NAS-based library of ripped discs, or from Tidal in high-res formats.


Two words come to mind when describing the Stellar S300: punchy and open. This is an amplifier that approaches its musical task with an enthusiasm that’s infectious. It manages to extract the essence and vitality of a performance with such glee that you can’t help but be drawn into the music.

This is an amplifier that has pace in abundance, easily keeping up with the most upbeat of recitals. It never allows the music to run away unbridled, but at the same time, it ensures that the sound never seems tethered or restrained.

Staging is generous, not only filling my listening room with sonic vistas, but ensuring that those vistas are presented with a sense of scale and air. There’s always plenty of breathing space for instruments and vocals, and the Stellar ensures that the broader, bolder swathes of sound don’t end up obfuscating the finer nuances of the music.

Yes sir, the slim S300 might sound fast and even furious at times, but it also has the finesse and the elegance to retain those details and subtleties so vital to the overall believability and emotive appeal of the music.

Fine imaging and focus harness the space and scale of the delivery and quantify it in three-dimensional terms, so that the music takes on an almost panoramic quality that makes the most of the music without having to resort to cold analysis.

Tonally, the Stellar doesn’t sound anything like the early iterations of the Class D genre. There is no hint of any edginess at the upper end of the spectrum, nor is there the clinical, soulless accuracy that was so impressive initially but would become fatiguing all too soon.

Instead, it’s the tonal breadth that pleases most, here: there is a wholesomeness, a tactile presence to the Stellar’s performance that adds to the overall sense of engagement: you end up wanting to hear more and more of your library under this amp’s auspices.

Van Morrison’s collaboration with organ ace Joey DeFranceso on You’re Driving Me Crazy (Sony Music) was gleefully rendered by the Stellar. It exploited the intimacy of the recording, but also made the most of the soaring, splashy organ and Morrison’s almost conversational vocals.

This is one of those sets that gets your feet tapping from the opening track, and while the recording’s focus is very much on the two main protagonists, the Stellar showcased the entire band’s contribution with equal verve.

‘Close Enough For Jazz’ is good case in point: here, everyone gets a turn, from the dexterous guitar and relentless stand-up bass to the boisterous brass. The cymbals crash with just the right intensity and the rim-struck snare sounds snappy and, well, just right.

If it’s scale and splendour you want, look no further than Hans Zimmer’s cinematic soundtrack masterpieces, as captured on Live in Prague (Eagle Records). The Blu-ray disc is masterful in surround sound, but the stereo mix on the double CD is no less compelling.

I’m not much of a soundtrack fan, but this production is one of my current go-to’s, thanks to a powerful and all-embracing sound that always sounds too densely arranged, too crammed with sonic action, to be emanating from just two loudspeakers.

In fairness, it’s a stern test for a system, with a tonal range that will relentlessly test the nether frequency regions, and can be equally punishing in the HF range. Lesser systems will wilt under the onslaught, but the Stellar seemed unperturbed.

It effortlessly recreated the vast 10 000-seater hall’s ambience, and captured the majesty and momentum, the tiny slivers of detail and the breathtaking dynamics of the music with a muscular confidence that allowed all the glory and intensity of the performance to come to the fore.

Downsizing to the intimate, binaurally recorded of Casey Abrams on Put A Spell On You (Chesky), the thrilling sense of realism, of being there, was even more pronounced. The Stellar brought the deep, resonant acoustic bass, the smooth but articulate guitar and the finely rendered percussion into sharp, vivid focus.

The stage depth and sense of ambience was particularly powerful, and while the recording often spreads the various instruments quite far apart, the thrust and cohesion of the music was always maintained. Each instrument was perfectly, wholesomely captured, but there wasn’t and sense of over-emphasised warmth or exaggerated saturation, either.

Instead, the Stellar always maintained its equilibrium, exercising control without robbing the music of its inherent soul and vitality. On ‘Nature Boy’, the mellow richness of the saxophone provided a riveting counterpoint to the finger-strummed bass, the brush-snared percussion and Abrams’ almost plaintive vocals. Pure, musical magic!


Here’s the thing: the Stellar S300 sounds like a big, beefy solid-state power amp with plenty of urge and loads of reserves. It’s smooth and melodious and meticulous in a way that’s almost tube-like, but with the impetus, agility and grip of classy solid-state circuitry.

Yes, it’s precise. No, it’s not clinical. And it never sounds harsh or harassed, even when approaching club-like levels. The Stellar S300’s composure never sounds even remotely under threat, and it rises to any occasion and every challenge with a certain delight that promises consistent entertainment, regardless of genre.

If the above sounds like the signature of a high-end amp, it is – and yes the S300 can and should be considered a high-end design. Which makes the price tag all the more remarkable. This is a power amp that won’t be disgraced in even distinguished audio company and punches well above its weight – quite literally!

By Deon Schoeman

Power output:
– 2x 135 watts into 8 ohms
– 2x 300 watts into 4 ohms
Frequency response: 10 Hz – 20 kHz (±0,5 dB, 2,8 Vrms, 4 ohms)
Signal-to-noise ratio: 100 dB (1kHz, 300 watts)
Damping factor: >1 100 (8 ohms, 50 Hz, 2,8Vrms)
THD + N: Inputs: 1x stereo RCA, 1x stereo balanced XLR
Outputs: Two stereo binding post sets
Dimensions (WxHxD): 432 x 83 x 366 mm
Weight: 3,63 kg
ZAR21 000

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Valve Audio Whisper phono stage
Sutherland 20/20 phono stage
Vivid Audio V1.5 loudspeakers

Van Morrison/Joey DeFrancesco – You’re Driving Me Crazy (Sony Music 44/16 FLAC)
Hans Zimmer – Live in Prague (Eagle Records
Casey Abrams – Put A Spell On You (Chesky 96/24 FLAC)
Neil Schon – Electric World (Virgin 44/16 WAV)