Sound wise on CD the SA-151S2 is fresh and vibrant, differently balanced tonally to Marantz players of old like the CD17 KI which had a ‘rounded’, warmer sound. The SA15-S2 detailing is excellent, sounding transparent through the entire frequency range with each note clearly defined. It is the SACD performance that is the real winner, the SACD playback throws a deeper, wider soundstage, tonally the music is more natural, fuller, and levels of detailing come to the fore that are glossed over and flattened by CD.  Hi-Fi News stated...”At £900 less than the SA-11S2 player, the SA-15S2 is almost a ridiculous bargain. It’s simply a delightful product.”

So is the SA-15S2 the ultimate contender? While it would be hard to argue its SACD quality, after spending time playing CD’s cracks start to show. The lower frequencies do not have the power, extension of some similarly priced stand-alone CD players, bass notes loosing impact and tending to soften.  Tonally the sound is leaner, harder with a colder upper frequency range; the overall balance on occasion is forcefully forward rather than natural. Both CD & SACD can sound ‘etched’ at times, but this tendency was more apparent on CD.

Getting Re-Wired

To the untrained eye the innards of the SA-15S2 would seen blissfully perfect, and in fairness the design and layout of the circuit boards would be unheard of at the price 5 years ago. Now look closer and one-by-one several areas of the digital & analogue circuits are ‘choking’ this player’s performance.

The OEM master clock is a basic pierce oscillator based on a single CMOS gate (74 series), quartz crystal whose output is buffered by a further logic gate. The clock circuit shares its power with the main 3.3V digital supply which also supplies the digital part of the DAC. The oscillator works by making the crystal unit filter the output signal of a CMOS gate, and sending it back to the input at a phase shifted sine-wave of some 100 mV amplitude. The 100 mV signal is mixed with an analogue input noise of 100µV and causes the oscillator to shift state slightly before or after it was supposed to. There is a ratio of 1000 between 100mV and 100 µV the raw signal to noise ratio can be calculated to 40 dB. At a clock frequency of 16.9344 MHz the division ratio to reach the audio sampling rate of 44.1 times 8 (352.8 kHz ) is 48. Thus the jitter level is also attenuated by 48 times or 33 dB. The total (time domain) signal to noise ratio is then 40 + 33 or 73 dB. Not at all enough to use the DAC chips potential of some 95 - 100 dB of S/N.

As part of our level-1 upgrade we remove the Pierce oscillator entirely and replace it with the Superclock 4-S. The ultra-low jitter performance of the 4-S immediately releases sound quality from the SA-15S2 and shifts the players tonality to remove hardness; the overall frequency range is more natural and unforced. Lower frequencies on CD playback have greater impact, weight and control. Greater dimension is added to music, vocals and instruments having improved spatial qualities and a more solid, palpable feel. To optimise the clock we add a Bybee Slipstream Quantum Purifier to the clock supply line, this instantly removes a layer of noise, unheard details emerge against a ‘blacker’ more silent background. The overall presentation is cleaner, more open and spacious with notable improvements in the low frequencies.

The next area to get attention is the regulated power supplies, they are aplenty but the main digital & analogue supplies use the generic 78xx series. We upgrade the 5V DAC analogue supply to a Super-regulator, version 3 board. This is a discretely designed regulator that uses 24 high performance components on a 4-layer PCB to achieve similar size to the 78xx series. The ultra-low noise, wideband performance of the discrete regulators drastically reduces noise at the DAC and associated circuitry on 5.0V power lines. This yields substantial audio benefits for both CD & SACD; the noise floor is reduced and the Digital-to-Analogue conversion process is more accurately executed yielding improved audio performance. To optimise the DAC board we replace the OEM choice of capacitors with a mix of Black Gate N, Sanyo OS-CON & Rubycon ZA types which are selected for analogue de-coupling, reference filter, etc.

Our hands now turn to the main board with replacement diodes for the analogue output stage power supply. Here we use HexFRED diodes which have lower noise, lower switching losses and superior sound to the OEM Schottky type. The general purpose digital power supply capacitors are upgraded to Panasonic FC whose lower E.S.R, improved sound furthers the performance.

SA-15S2 Maxed Out

We take the SA-15S2 much further with the Level-2 modification with 2 additional stages of discrete regulator power supplies using the Invisus 2 boards. The new regulation is included for the 8.0V digital (8VD) and 8V main (8VM) circuits. We add the Superclock 4 power supply to the master clock, and the benefits here are twofold. Firstly the dedicated clock supply isolates the master clock power supply from the internal supply, secondly the clock is now powered from an Ultra-low noise, wideband DC source.

Next we undertake extensive digital power supply upgrades, all diodes are upgraded to HexFRED for the DAC power supplies, general purpose power supply reservoir & bypass capacitors with the high grade Panasonic FC. For the main analogue output stage supply we replace the Elna ‘For Audio’ power supply capacitors with Elna Silmic II type, the highest grade in the Elna series. Analogue output signal coupling capacitors are upgraded to Black Gate N for improved transparency, tonal purity.