So we reach the final instalment of our four-part series advocating clean power in audio. What was meant to be a single article covering cables and extension blocks spread, the required critical listening proving demanding at times. None more so than in the last article assessing mains cables; the things we do to advise and guide you.

Joking aside, mains power was the last main outpost of audiophilia I personally hadn’t addressed. Sure I’d dabbled, using a not-inexpensive mains cable for example. I’d always assumed it was doing some good (and no harm). I’d just never sat down and compared it to alternatives, be that a megabucks cable or standard IEC kettle lead. That’s now been rectified.

The final piece of the jigsaw is mains conditioning, something I hadn’t tried despite being a convert to external power supplies (where appropriate). Strange given they both address the same problem of electrical noise. So let’s sort that by looking at two offerings, the V5 Polaris from Isotek and the Niagara 1200 from Audioquest. 

It’s not a like for like comparison, not least because of the price differential (£695 for the Isotek, £1099 + cable for the Audioquest). So think of them as different rungs on the mains conditioning ladder, the key questions being: –

  • Do they sound better than standard low-cost mains blocks, the sort we all use around the home
  • If so, does the Niagara 1200 justify it’s higher price?

Design & functionality

Other than price the most obvious difference between the two conditioners is the provision of two higher-current outlets on the Niagara (alongside its five lower-power filtered outlets). The V5 Polaris keeps things simple by providing six lower-power filtered outlets. 

Why the need for high-current outlets? Because some devices, most notably power amplifiers, need higher current capability. Filtered outlets constrain the current, which impacts the sound, particularly the dynamics. Or so the theory goes; it’s something we will listen for. 

Note that Isotek also makes conditioners with higher-power outlets, it’s not a technical point of difference with Audioquest. More a marketing one, reflecting different features at different price points. 

In terms of functionality, both the V5 Polaris and Niagara 1200 offer surge protection, the Isotek specified at 45,000 amps, the Audioquest described as non-sacrificial. Whichever, don’t underestimate the peace of mind this brings. Each device strives to minimise ground noise derived from the earthing arrangements; all outlets on the Isotek are star-earthed, the Audioquest uses the company’s patented Ground Noise-Dissipation System. 

The internal wiring in the V5 Polaris is multi-strand 6n OFC silver-plated with an FEP dielectric. The Niagara 1200 uses ultra-low resistance solid-core wiring optimised for low-noise directionality. Each company stresses the use of high-quality components inside their conditioners. 

On both the Audioquest and Isotek all outlets are independent of each other, reducing differential noise. The V5 Polaris’ filtering is also significantly better than the previous model, the net of which is a reduction in differential noise of 20dB at 1kHz (increasing to 42dB at 10kHz).

Both conditioners feature an on/off switch, with an LED to show their state. The V5 Polaris comes with one of Isotek’s Initium cables to connect to the wall socket (available separately for £99). The Niagara 1200 comes without a cable. You can use a standard kettle lead, Audioquests recommends one of its own, not least to maximise the grounding-noise dissipation. I mainly used a £135 NRG-Y3. 

Finally all Isotek V5 models include a system-link outlet to daisy chain additional conditioners. Useful if you have a limited number of wall sockets available, although maintenance of the star-earthing across all outlets is probably a bigger factor. Audioquest tells it as it is; the Niagara 1200 is most definitely NOT designed to have another conditioner plugged into it. 

Looks and build quality

Both units look the part, the V5 Polaris finished in silver with black sockets. The LED splits the two banks of three outlets, which sit on top of the unit. On one end is the mains inlet and power switch, the other the system-link outlets. Build quality is nice and solid.

The dark-grey Niagara 1200 is an even more substantial unit, weighing in at 8.2 kg against the 1 kg of the Polaris. The Audioquest is also twice as deep, with the sockets and power inlet sitting on the front. You can use it on its feet, on its side or on its front, which enhances flexibility. I found that useful, but equally had no problems positioning the V5 Polaris. The Niagara’s build quality is very sturdy.

And so to listening

The system used for listening was the same as for the power cable review: a Musical Fidelity A1 amplifier, Cambridge Audio Edge NQ streamer and Mo-Fi Sourcepoint 8 speakers. Around £10k in total.

With the Niagara 1200 the amplifier was fed by one of the high current outlets, the streamer by a lower-power outlet. On the V5 Polaris both went into lower-power outlets. With both conditioners low-cost kettle leads (the sort that power your kettle) went to the amplifier and streamer. 

Finally, after the main listening, I maxed out the Niagara 1200, using the expensive Blizzard cable to connect it to the wall outlets and two NRG-Y3 cables going from conditioner to amplifier and streamer.

Isotek V5 Polaris

Up first was the Shinya Fukumori Trio and For 2 Akis, whose first track ‘Hoshi Meguri No Uta’ is delightfully pared-back contemporary jazz. Stark piano chords open the piece, joined first by delicate, almost sparse drumming, then a breathy tenor sax floating above. Very gentle, superbly played with great interplay. And well recorded, not least for the sense of acoustic that’s portrayed. All in all, beautiful music that sounded lovely through the standard mains block. ‘Do I need anything more?’ was my first reaction.

The V5 Polaris answered that in the affirmative, and quickly; the improvements were obvious. The opening chords were more reflective thanks to a quieter background. Transients on the cymbals and high hat were crisper, the sax clearer. Subtle nuances could now be heard thanks to greater detail being extracted. And the feeling of being there, the acoustic realism, was a distinct step up.

Next up was the high-octane ‘First Wave Intact’ from Secret Machines’ Now Here Is Nowhere. If you want to test dynamics this is your track. Again, it was no contest, the standard mains block sounding decidedly muted. Like the Sunday morning version, more polite so as not to offend the delicate head. Switching to the V5 Polaris brought energy to the track. The Saturday night version, the one that inspired that delicate head in the first place. More detail, more zing (aka transients), better clarity. And significantly better dynamics. Overall the V5 Polaris cut through the sound to present a far more realistic take on surprisingly well-crafted rock.

More listening ensued, each track confirming the superiority of the Isotek conditioner against the everyday mains block. I sensed I was already sold on mains conditioning per se. I could also live with the V5 Polaris, its benefits worthwhile in the context of the system being used. But how would the Niagara 1200 fare in comparison? Time to find out. 

Audioquest Niagara 1200

Against the stock mains conditioner it was no contest. Using the same tracks as above everything just sounded cleaner through the Niagara 1200. The big question was therefore how it would perform against the V5 Polaris.

In short, the Niagara 1200 delivered the same sort of benefits, just slightly more so. Greater clarity, in turn leading to even more detail being heard. Firmer bass. Better transients, allied to which the dynamics were notably stronger, even quieter music benefitting. Musically the impact was greater nuance, subtle textures coming through, an even more live feel to the sound.

Standout tracks included ‘Honiara’ from Snarky Puppy’s Empire Central. As often with the jazz combo the album was recorded live, this time across 8 nights in Dallas, Texas. With 19 personnel listed in total (eat your heart out Earth Wind & Fire) it was always going to be a busy album. The Niagara 1200 separated out the different contributions better. The opening horns blasted out even more fiercely than with the V5 Polaris. Electric bass was better defined and had more texture. All in all the track just had more verve to it, as befits a good live recording.

With ‘Hoshi Meguri No Uta’ the Niagara 1200 captured the delicacy better, the sense of anticipation heightened by quieter backgrounds. 

And Gerald Albright’s ‘Sooki Sooki’ from the album 30 positively exploded from the speakers, the dynamics even more impressive through the Niagara. It also added weight to the track, firming up the impact of the bass and synths. In heavyweight boxer terms more of a sculpted Anthony Joshua than Tyson Fury, even if that analogy exaggerates the differences. 

How much of the improvement was down to the higher-current outlet was difficult to say but the Niagara 1200 definitely took things to the next level. As it should at nearly twice the price (allowing for cable). It did feel as though constraints had been lifted though, as if the system was performing nearer to its full potential. No, the comparison didn’t embarrass the V5 Polaris at all; reputations were not slain, no opinions changed as to the Isotek’s efficacy. The Niagara 1200 just upped the ante a little further.

Pimp my ride

That was with the Niagara 1200 being used with lesser cables. Time to shoot for the moon, so in went the £650 Audioquest Blizzard between wall socket and conditioner. From that Audioquest NRG-Y3 cables fed the amplifier and streamer. Adding a substantial £800 to the price, now just over £2k in total. Ouch.

Yet, ignoring the price tag, it has to be said the cables made a difference. One that was easier to hear than when comparing cables without a mains conditioner. ‘Hoshi Meguri No Uta’ had an extra purity to it, a slight burnishing of the sound that embellished the feeling of being there. Serenity was enhanced, the saxophone was cleaner, the cymbals cut through the arrangement better. All very marginal differences it has to be said. All audible though. 

Moving up a gear, Secret Machines’ ‘First Wave Intact’ was also cleaner, the components making up the wall of sound easier to distinguish, treble slightly more explicit, more detail allowed through. There was greater separation between lead and backing vocals for example. A tad more dynamic sound too. Again they were all marginal improvements. They helped communicate the musical intent better though.


When reviewing mains cables in isolation (here), critical-listening mode had to be turned up to 11. Differences were sometimes difficult to hear. Those that did surface were often of academic rather than musical interest. 

Not so when assessing mains conditioners. The improvements the V5 Polaris and Niagara 1200 brought were easier to hear and gave better insight into the music. The lower noise floor resulted in a clearer sound, one that allowed more detail through. Meaning quiet music was more nuanced. With louder music it was easier to hear the constituent parts. Palpability of performers was also enhanced, as were dynamics. 

Both conditioners performed well, fully justifying their respective prices. Sufficiently so for them to merit Hifi Starters Best Buy awards.

Yes, that’s in the context of a £10k system. No, Hifi Starters shouldn’t rush out and splash half their budget on one of these conditioners. Over time, as you upgrade, there’ll come a point where mains quality is worth considering though. And given the lower-cost options available that may be sooner than you think. Isotek’s £120 EVO3 Isoplug worked well for me for example. The company’s V5 Gemini conditioner is a two-socket version of the V5 Polaris, yours for £399 + cable. Ideal for powering two sources maybe. Or consider Audioquest’s PowerQuest series, which sits under the Niagara range (UK versions should be available early next year I’m told).

All in all, mains quality is a complex subject but one that shouldn’t be ignored if you want to get the most out of your system. Yes conditioners are expensive, effectively a component in their own right. They do make a difference though, one I’m pleased I’ve now heard first hand. My only regret? That I didn’t address the subject earlier.