The Auditor is SPL’s interpretation of a no compromise, high-end headphone amplifier. They have strictly followed a purist approach to achieve the highest sound quality.

The basis for such high-end developments is SPL’s proven 120 volts reference technology. The core elements are the handmade SPL SUPRA op-amps running on 120 volts, which corresponds to approximately twice that of most modern analogue audio semiconductor technologies. Using the 120 volts circuitry and processing SPL reach performance levels far beyond conventional designs in dynamic range and distortion levels, and such technical specifications exceed all known analogue or digital standards.

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Why Headphones?
There is more than meets the eye to working with headphones. For example the  modern audio production is often a decentralized process, maybe recording and track laying in one studio and mixing in another and as a result a production often takes place in acoustically questionable rooms. In such circumstances, a mix might occur in an acoustically deficient ambiance (for example, in an extremely modal room), and employing headphones then begins to make sense when a successful mix would otherwise turn out to be impossible.

Another fact is that many musicians or producers might wish to mix at home or small studio environments, this is when headphones become an absolute necessity, enabling an evening or late night session that can only take place thanks to it being unhindered by the local acoustic environment.

Acoustic Magnifier
When working with full range monitors in the studio, headphone monitoring is an extremely important alternative to loudspeaker monitoring: analytical monitoring via headphones offers a very high precision to observe details. Headphone monitoring is like working with an acoustic magnifier, excluding external room influences. Working with the magnifier effect of headphones has the advantage of safely hearing clicks or similar defects and helps in fine tuning crossfades or to judge tonal problems in individual tracks.

The End of Ear Fatigue
With headphones, ear fatigue can creep in relatively soon, and there are several causes. The first being is that quite simply, some headphones are very uncomfortable to wear. Moreover, a standard headphone amplifier is often an additional important reason for premature ear fatigue. Almost without exception, present-day headphone amplifiers employ comparatively undemanding IC’s. In the best cases headphone amplifiers might work with symmetrical voltages of +/-15 V to +/-18 V, and in less favorable cases, with only a simple supply of 9 or 12 V from cheaper external “wall-wart“ power supplies. But the voltage level acts in circuitry much like the cubic inch capacity to the productive power of a combustion engine: Cubic inch capacity is replaceable with nothing but more cubic inch capacity – and in the productive power of electronics, voltage level functions similarly.

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For some years, now, SPL has addressed this issue in all of its mastering product series through its own specifically developed 120 volt technology. Consoles and signal processors of the SPL Mastering Series appear as central elements in installations of today’s most renowned mastering houses (e. g. Bob Ludwig’s Gateway Mastering & DVD in the USA, Simon Heyworth’s Super Audio Mastering in Great Britain or the Galaxy Studios in Belgium). This 120 volt technology is based on discrete operation amplifiers from SPL’s own production, developed and perfected over many years by SPL’s co-founder and chief developer, Wolfgang Neumann. The SUPRA OPs have a signal to noise ratio of 116 dB and offer a 34 dB headroom – that yields an unequalled 150 dB dynamic range.

The musical result is not to be mistaken: Regardless of the monitoring means, regardless of how loud you monitor – the Auditor always remains a distant, impartial factor unaffected when used to capacity and beyond being overloaded. The phase stability is always perfect, its THD next to immeasurable. The SUPRA OPs cannot be stressed in the most stressful circumstances, and for precisely this reason its musical sound is always relaxed and spacious. All frequencies are reproduced in balance, basses are stable and tight, mids are clear and differentiated and highs remain transparent and soft.

Such supreme and heretofore unreachable neutrality in audio reproduction is the direct consequence of our technical approach and basis in 120 volt technology: Possible disturbances from such as noise or distortion are so slight that we even arrive at the boundaries of the best measuring equipment, and what remains is quite simply unaltered musical sound.