AudioQuest PowerQuest 303 Power Conditioner & Surge Protector with NRG-Y3 Power Cable Review – Cleaners From Venus

The $459.95 USD PowerQuest 303 power conditioner & surge protector and a $189.95 USD 2m NRG-Y3 power cable were kindly provided by AudioQuest for my review – and I thank them for that. I tested the devices over a period of 9 weeks.

Introduction

I am a scientist. Throughout my long career, I have contributed to knowledge, be it by publishing in the academic environment or gathering and passing on experience in industry all over the world. You need an open mind on this path – and lots of patience. I also have a thorough classical music education from my earliest childhood to high-school graduation.

It is therefore not surprising that scientific progress in music reproduction interests me. Since the early 1980s, when hanging out in HiFi shops, I had heard of power conditioners but was always deterred by their price and their mystery. After all, my mid-priced stereos sounded good.

AudioQuest have produced mainly digital & analog cables and power accessories since 1980. The company polarizes. For some, their products are snake oil, for others, they are the saviour of their stereo’s sound quality. I have been a customer for some time, mainly purchasing their lower-end digital and analog cables as these are made well and provide good value.

Reasons enough for me to test theory and its application when AudioQuest offered me their PowerQuest 303 12-Outlet Power Conditioner & Non-Sacrificial Surge Protector and an additional NRG-Y3 power cable for analysis. The idea behind this combination was to connect the 303 via the NRG-Y3 to the mains outlet, then plug up to 12 electronic devices into it. The expected result is sonic improvement through minimization of noise.

The question is, does it work, and, if so, how is this accomplished?

Let’s first discuss “noise”: what is it, what effect has it? We then have a look at the products themselves, and finally discuss their performance.

Noise?

Yes, noise is real! There are two principle kinds of noise, electromagnetic interference (EMI) and radio frequency interference (RFI) (there is also high-frequency switching noise between 500 kHz and 2 GHz in switching mode power supplies which we ignore as it does not apply here).  By definition, interference originates from a source external to a signal path and produces undesired artifacts in the signal, which affects sound quality.

Noise comes from our music sources such as streamers, computers, and phones via USB cables, from our amplifiers, DACs, and their power supplies, and from the power grid. AudioQuest’s Senior Director of Engineering, Garth Powell, claims, some of it comes even from our atmosphere (well, there’s lots of radio waves around, think of cellphone towers, Bluetooth devices, AM/FM etc).

USB Noise

I keep this short as the PowerQuest 303 and the NRG-Y3 cable do not address this noise source. You need an Audioquest JitterBug Full Metal Jacket and/or an ifi Audio iPurifier 3 to mitigate this problem.

Computer and phone internals are inherently noisy. If our DAC is powered through the USB port, the computer delivers both noisy power and a poorly timed data stream (“jitter”) caused by RMI and FMI through VBUS and data line, respectively, to the DAC.

Noise from Power

The electricity (AC) comeing out of our mains contains RMI and RFI, the amount of which depends on our living environment. It will be worse in a city apartment building than in a house in the country, and it may fluctuate with the time of day.

Power supplies convert AC to DC to drive the equipment. RFI is generated in the diode bridges of our equipment and picked up by (unshielded) power cables. So we get interference and therefore sound degradation from both directions.

Noise from the power grid (AC), is typically minimized by filtering through power cleaners/conditioners (such AudioQuest’s PowerQuest and Niagara series), by sophisticated power supplies, and by complete power regeneration (e.g. PS Audio’s power regenerator). It can be backwashed by the electronics as we have experienced with the EarMen Sparrow dongle DAC.

Power cables draw the largest current and therefore produce the largest electromagnetic field (compared to audio cables). Cords with wires shielded inside reduce this electromagnetic field and also mitigate the noise incoming from our equipment by avoiding magnifying the interference patterns.

How does Noise sound?

Noise is defined as “unwanted sound“. True, all this noise palaver, but rarely anybody explains what we actually hear when our audio signal is “noisy”? That’s because noise is superimposed on the audio signal, it is an impurity that alters it and what we hear is the combination of both. Call it unorderly layered. But when we remove this superimposed noise component/layer from the audio signal, we should hear a difference…and hopefully to the better.

According to Garth Powell, “cleaner” sound is less muffled and therefore clearer. Co-blogger Alberto, who uses the AudioQuest PQ3 and the NRG-Z3 power cable reports variable effects depending on the connected equipment, from zero to “better bass definition and control, airier treble, and an overall more effortless musical flow“.

To make this clear, the noise cleaning effect is zero, when it is not needed.

Co-blogger Biodegraded reports better textured and more extended bass and a quieter background throughout in his headphone amp with the ifi Audio iPower power supply.

I compared the stock power supply of the Burson Funk amplifier with the Burson Supercharger 3a switching mode power supply. The Supercharger 3a wall wart yielded a much clearer, more transparent sound with better note definition, better accentuation, and better imaging in the Funk. No A/B-ing required. The Funk’s sound with the stock power supply sounded muffled and closed in in comparison. The Supercharger allegedly filters out noise during conversion from AC to DC.

An example of USB noise is shrillness and a bright/thin midrange in the sound of the AudioQuest DragonFly Red dongle DAC. Adding the JitterBug FMJ to the chain, the sound becomes richer with a deeper stage, but the soundstage gets narrower. Biodegraded did not like this effect (with his equipment) and sent me one of his two JitterBugs. Thank you very much!

We learn: such cleaning can go sideways, too. It’s trial and error!

Noise Mitigation

My Wishful Thinking

We have to deal with noise coming from the power grid (AC), from the air, and from our equipment (DC), which may influence sound quality. So, ideally, we need a power cord that filters noise right at the power outlet and dissipates noise on the way to the power conditioner or equipment. Whether this is scientifically possible is another question.

As a minimum, the cord should be shielded by a jacket, and internal wire strands should be shielded against each other to minimize or even avoid magnification of EM interference. Twisted wires minimize contact area and hence interference. And the power cable should be kept away as far as possible from RCA cables.

A power conditioner should also filter noise, ideally from the incoming power cords on either side, that is noise from the AC direction and from the equipment. Again, whether this can be done by current technologies I don’t know.

An ideal power supply should also filter noise by itself .

USB noise from the computer is best mitigated by splitting power and data lines by deploying an external quality power supply that minimizes power noise, and having the digital signal reclocked by the DAC.

Company Claims

Disclaimer: in this chapter, I attempt to summarize the scientific claims of companies in layman’s terms as a base for discussion. They do not reflect my own research or opinion.

AudioQuest and Shunyata Research are just two of the companies that develop premium power cords and power conditioners. Shunyata entertain the idea that most of the noise comes from the equipment; power cords are “antennas” that pick up noise so that Hifi components “infect each other with the noises they generate” (= the “backwash” mentioned above).

If you put a noise filter against the outside power grid, it will act like a firewall and push the noise back towards the stereo system. Their solution is omnidirectional filters for noise absorption in their power cables. The cable becomes the extension of the components’ power supplies that captures (some) of the noise that leaves the component.

AudioQuest have released a comprehensive “White Paper – Power Demystified“. According to them, noise is introduced to the system through the AC power grid and backwashed from components (cf. Shunyata above), but also through the air (radio frequency noise from cell towers etc.).

These noises “couple onto the audio and digital signals” and “distort, mask, and remove” content from low-level signals [= unamplified signals at low voltages such as from DAC, pick up etc.]. AudioQuest power conditioners and power cables are designed to filter and dissipate as much of this parasitic energy as possible.

The PowerQuest 303 12-Outlet Power Conditioner & Non-Sacrificial Surge Protector

Purpose

The AudioQuest PowerQuest 303 is the lowest priced of their power conditioner line. It has principally three tasks:

• Mitigate noise (as discussed above) from the AC grid and backwashed from the equipment
• Protect the equipment from power spikes in a non-sacrificial way [that is the 303 is not damaged by power spikes]
• Avoid power fluctuations: always provide high-current devices such as power amplifiers with sufficient power

The PowerQuest 303 features 12 power outlets in the back, 8 linear [=evenly] filtered for source components (DACs, phono stage, CD-player), and 4 high-current ones for power amplifiers, active speakers, and other electrical-current guzzlers. The difference between these outlets is that power amps are current hungry AND don’t have a constant power draw; they need a higher current for transients (let’s say a furious trumpet solo). These high-current circuits deploy low-impedance technology. AudioQuest calls this “Low-Z power technology”.

If an amplifier does not get enough current [AudioQuest calls this “current compression”] it sounds muddled and anemic. A good example is connecting the notoriously current-hungry final E-5000 iems to a low-current providing dongle DAC such as the AudioQuest DragonFly Cobalt, which makes the bass sound pillowy.

As a non-sacrificial surge protector, the PowerQuest 303 will accept power surges/spikes of up to 6000 V or 3000 A without taking damage. It hence has to be switched on all the time. We calculated a maximum power consumption of 60W.

As a noise cleaner, the PowerQuest 303 is claimed to address the AC noise from both the grid and the DC noise backwashed from the Hifi components. It will not filter any radio-frequency noise picked up from the air (you will have to go a higher level model).

Physicals

The PowerQuest line consists of quite large square boxes of the size of a Hifi component. I was initially shocked as I did not know where to put the 303 until I found a place previously occupied by a VCR. The chassis is largely made of polycarbonate with the 12 outlets in the back and a very dim green LED and a power switch in the front. The PowerQuest 303 stands on four rubber-foam textured polymer feet and develops no heat. Set it (anywhere you want) and forget it!

Brackets for rack mounting are included. As everything I have from AudioQuest, the device is built well. Also included is a rope-like/garden-hose-like 2m 14 AWG power cord (PQ-415) that does not appear to be sold separately. It incorporates some of the technology of the NRG series. I was told to use the upgrade cable NRG-Y3 to connect the 303 to the power outlet, and use the PQ-415 for connecting an headphone amplifier to the 303.

This order was probably recommended because the first power cable in the chain is also the connection to the ground.

As a rule of thumb for audioreviews.org contributors – call it a hypothesis for us to test: a headphone amplifier is more affected by the power quality (some claim 70% of sound quality depends on it) and a DAC more by the data-line quality.

Consequently, an amplifier should benefit more from the PowerQuest 303 and the NRGY3 whereas a DAC benefits more from a clean USB source (but clean power is also important for proper clock detection). The effects of a high-quality power supply can be “overwritten” by a DAC’s distortion (poor dejittering/resyncing/rebalancing).

The NRG-Y3 Power Cable

The NRG-Y3’s task is, according to the manufacturer, to minimize distortions and to “drain away” (=dissipate) noise. This is claimed to be achieved by asymmetrical copper grains (“directional conductors”), minimal strands interaction, minimal impedance (for optimal current transfer), and silver-plated shield drains. I have no way to test this, of course.

Whilst it is true that fewer grains mean fewer grain boundaries, which results in a decreased electrical resistivity, it remains to be seen (or rather “heard”) how this affects sound. But, if this noise dissipation worked as claimed, this would explain why the “last 2m” of the power line make a substantial difference, a main argument of skeptics against premium power cords (in comparison, Shunyata claim that the gremlins are reduced by omnidirectional filters).

The NRG-Y3 is of robust build with a braid textile jacket. The polycarbonate-coated plugs on either end are NOT as bulky as those of a typical premium power cable.

Testing The Devices

I plugged the PowerQuest 303 via the NRG-Y3 into a wall outlet and used it for about 9 weeks continuously. I first plugged the EarMen CH-Amp via the included PQ-415 power cord into one of the four high current outlets (followed later by the FiiO K17 DAC-amp combo). The linear power outlets I used for the SMSL DO200 MKII DAC (feeding into the CH-Amp), and a new Mac Mini M4 with BenQ MA270U 27 inch display).

During the test period, I continuously added higher quality equipment such as the ifi Audio iPurifier 3 for cleaning the lines between the computer source and the SMSL DAC, and the Meze POET planar magnetic headphones. And even with these $2000 cans, I found the sound quality left room for improvement.

As music sources, I used the Mac Mini and two different iPhone (16e and SE 1st gen.)

After 9 weeks, I disconnected the CH-Amp and SMSL DO200 MKII DAC and plugged them with their stock power cords into a Belkin powerstrip.

The Result

I was anxious as to whether I could hear a clear difference. After all, if improvements with devices like the PowerQuest 303 were debatable, they are not worth their money. No “golden ears” required.

When I eventually started listening to the “unfiltered” SMSL/Earmen combo (still with the iPurifier 3) with the Meze POET headphones, I was instantly very disappointed. The sound was comparably flat and uninspired; dynamics, transparency and sparkle were lacking. Too much was missing for my gusto. It took me some time until my brain’s burn in of the sound with the PowerQuest 303 was erased and my ears adapted to the changes.

I am sure I would have been perfectly fine without the PowerQuest 303, but once I had heard the difference, there was no way back. Evil!

I certainly do understand why some people are skeptical as the effect of a device such as the PowerQuest 303 is not black and white. It rather relies on many factors that are different for each setup, location, and even time of day. It also depends on how sensitized the listener is. If I listen to Metallica, I don’t need any filtering, but I do when playing, let’s say a symphony or beautifully recorded Japanese jazz of the 1970s.

Value

Is the PowerQuest 303 worth its price, which buys you 10-15 regular power strips? This entirely depends on the value of your equipment and your spending habits. But you will likely have the Powerquest 303 for longer than your electronics as it is laid out to last for 20 years. The same accounts for cables, by the way. After a one-time expenditure, it is a gift that keeps on giving and it also provides piece of mind.

Concluding Remarks

The AudioQuest PowerQuest 303 works for my setups, not only as a protection from power surges, but it also reduces sound deterioration. It is still no miracle cure as it does not address all noise sources, for example the signal coming from the music source through, let’s say, a USB cable. Whether the sonic benefits I experience are the results of the company’s physics claims I cannot verify.

In the end, the path to knowledge always leads through trial and error. Per aspera ad astra. A painful, repetitive process.

And this, dear attentive reader, you have to do yourself.

Until next time…keep on listening!

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