FAQ

• Input impedance:
  The input impedance of the icOn depends on both the power amplifier’s input impedance and the current volume setting, so it varies with every volume position. The lower the volume, the higher the input impedance. At normal listening levels, it is higher than 1 MΩ. At 0 dB, the input impedance of the icOn equals the input impedance of the power amp. At +1, +2, or +3 dB, it becomes slightly lower than the amplifier’s input impedance.
• Output impedance:
  The same principle applies to the output impedance, but in the opposite direction. The lower the volume, the lower the output impedance. At typical listening levels (around –20 dB), it is only about 1/100th of the source’s output impedance, plus the copper resistance of the Slagle autoformer, which is approximately 70 Ω.

The good news is that impedance matching is automatic with an AVC (or TVC). They provide the best possible impedance conditions for both the source and the power amplifier. This is a major advantage over resistive stepped attenuators and explains why autoformers are generally the superior choice.

Autoformers transform impedance. At -20dB, output impedance is ~1/100 of the source impedance, and input impedance is ~100× the load. This can even solve impedance mismatches that would otherwise cause sonic degradation.

For home audio, yes — unless your amp has very low gain or low sensitivity, 10V will force you into extreme attenuation and hurt S/N. I can modify the icOn to handle it properly if I know your system chain.

Yes, as long as they’re low capacitance (<100pF/m). I recommend Van Damme professional cables.

Multiple outputs that can be activated individually or in combination via remote — useful if you run multiple amps or headphones without always having them paralleled.

Yes, the new icOn 5 Zen has a smart mono function (L+R, left only, right only).

It uses a high-quality optical encoder, common in high-end gear, not the “fast-turn” feel of mass-market devices.

For ±0.1dB attenuation match: typically 20Hz–40kHz depending on source/load impedance. For ±2dB FR: ~10Hz–80kHz with a low-impedance source.

A good TVC typically achieves 10Hz–40kHz.

Yes, if your source outputs at least 1.5V. Lower-output sources (e.g., some MC phono stages) may not reach full power.

Perfectly fine — the icOn loves high input impedance loads.

Many customers think so, especially if they value transparency, speed, and noise-free performance. But preferences differ.

The autoformers don’t change with use — any perceived “break-in” is likely your brain adapting to the cleaner, more transparent sound.

So if you ask me about the icOn’s burn-in time (or break-in), I would say that there is no burn-in for my icOn preamps. The copper wire and magnetic cores simply don’t change in the short term (within a few years). However, many icOn customers report that they notice an improvement after around 100 hours of listening.

My understanding and experience is that this improvement happens in the listener’s brain, not inside the preamp. Autoformers produce a sound that is quite different from resistive passive attenuators or active preamps. Our brain “learns” this new sonic experience and adapts to the complete lack of background noise and distortion — the higher transparency. Some audiophiles call this adaptation “burn-in.”

I’m an engineer and a music lover, but I prefer to stick to scientific and engineering facts. Maybe I’m wrong about the science — who knows? As always, YMMV… your mileage may vary. 😊

Sorry, but a linear power supply will not improve the sound of an icOn 5. The external wall wart is not directly connected to the signal path — that part of the circuit is fully passive — and it is galvanically isolated from the internal power supply circuits. The display lighting and the microprocessor cannot detect any difference between an SMPS and a linear power supply.

The problem with SMPS in the audiophile community largely comes down to generalisation. Yes, 20–30 years ago it was often true that linear power supplies performed better. But today, this is simply no longer the case. Modern high-frequency switching devices and advanced circuits often outperform traditional 50–60 Hz linear supplies. Most audiophiles don’t have the measurement tools or proper A/B testing setups to evaluate this, so the “maybe I can hear a difference” bias persists — often based on outdated information from self-appointed experts without technical training.

A few facts the power-supply “experts” usually overlook:

1. When the switching frequency is 100–1000× higher, it becomes much easier to filter and suppress noise (50 kHz–1 MHz instead of 50 or 60 Hz).
2. Noise and EMF from an SMPS are proportional to the current drawn. There is a huge difference between the SMPS used in a power amp and the very low-current SMPS I use.
3. Modern digital audio devices are filled with tiny SMPS modules embedded on the PCB. Audiophiles don’t see them, don’t know they’re there, and never complain about them — but the visible wall wart is immediately treated as “suspicious.”

There are many other factors audiophiles generally don’t consider. My completely honest opinion: the SMPS I use is not inferior to a pure linear power supply.

From 2016 to 2019, I used TVC transformers from SAC Thailand. They were good, but not the best. Today, the finest magnetic attenuators are the autoformers made by Mr. Dave Slagle. They deliver a significantly better, more transparent sound with no coloration. I use only the custom copper autoformers that Dave Slagle builds specifically for me according to my specifications. Our silver autoformers are produced in-house.

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