Blog #12
Curiosity is a good thing......
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My loan Audio Note (UK) level 4 S4 step-up transformer (SUT) (RRP £6400 as of Sept 2026) sits cosily on my rack.
What's going on here?
Well, the title says it all...curiosity, plain and simple.
I am a keen reader of hifi reviews, mainly on Audio Note (UK) products, as that's my sphere of interest.
I've been really enjoying Jeff Day's ongoing series of reviews on Positive Feedback (reviews HERE) over the last few years and avidly await any new updates.
On 12/03/20, Jeff received the level 4 Audio Note S4 SUT to review alongside the Audio Note IO moving coil cartridge and AN V interconnect cables (review HERE)
He was incredibly impressed; even after the first sneak-peek listen, he reported:
"The Audio Note (UK) AN-S4/L step-up transformer sure has made a good impression. The sound is natural, detailed, rich, and superbly musical. This is what music playback should sound like!"
I own the IO cartridge and still have the AN V cables on loan, the same items Jeff Day was using, and a chrysalis of an idea germinated in my brain....
So...you're not happy with your systems sound then?
Far from it.
I built my system carefully to fit within the Audio Note performance-level system.
(Link HERE) I have referred to this in previous blogs, as it is a framework for constructing an Audio Note system and ensuring all components work harmoniously with each other.
I can 100% attest that this framework works; my system, as I see it, has (to me) no audible flaws and wows me every time I press play on the CD or drop the needle on the turntable. The S2 SUT is splendid, and the vinyl replay is, to my ears, unmatched.
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Couldn't resist a picture of the vinyl reply half of my Audio Note (UK) system, I really do love the look of the aluminium fascia against the light oak shelves. CD on new vinyl storage shelf to the right.
Apart from the review, what made you want to compare the S4 SUT in particular?
Firstly, while I was researching the S4 SUT, I thought I would speak to Audio Note (UK) directly and was happy to speak with Peter Qvortrup himself (the Audio Note (UK) founder). He very kindly gave me a lot of his time and explained that the S4 differs from and improves upon my S2 in 2 important ways:
a) My S2 has cheaper core materials; it has an 80% mu metal, which is a lesser grade than in the S4, and copper wiring throughout.
b) The S4 has 99.99% pure silver-wired coils and a fully interleaved super mu-metal 250 core.
The silver wire maximizes clarity and detail, and the core ensures high magnetic permeability and precise signal conversion.
He stated that these 2 major differences make a SUBSTANTIAL sonic improvement.
I was intrigued. Substantial, eh? Over my S2? That'll be a tough gig......
Secondly, in blog #11, I was so impressed with the sound of the AN V silver interconnect cables in my system (Blog #11 HERE) that I wondered how a silver-wired SUT would perform, with a LOT MORE silver wire than the AN V. I've kind of caught the silver itch, and it definitely needed scratching!
Thirdly, I find the idea of adding the otherworldly level 4 S4 SUT to my level 2 system to be of considerable interest, and I'm sure you're as curious as I am!
According to the performance-level system, it shouldn't really work... am I up for the challenge? YES. Plus an additional YES for emphasis.
Don't tell me, the well-used begging bowl came out again....
You know me so well! Yes, on to Micky at Audio Note (UK) HQ again, and to my delight, the ever-efficient Lily was sending out a very well-run S4 for me to listen to and review.
The moment captured when I first dropped the needle on the incredible "Swing Era 1937-38 LP by Time Life Records with the S4 SUT in place.
Tell me more about the S4, I'm intrigued....
AN S2 SUT - level 2
(RRP £1450 as of Sept 2026)
The internal transformers used in the AN-S2 are manufactured by Audio Note (UK) exclusively, use the very best core materials and winding technology available at the price, and are housed in Mumetal screening canisters to minimise noise and interference.
Its cost comes from it being hand-assembled, a premium-grade audio component built with high-specification custom parts.
AN S4 SUT - level 4
(RRP £6400 as of Sept 2026)
The internal transformers used in the AN-S4 are manufactured exclusively by Audio Note (UK). Each exclusive, custom engineered transformer is made from 0.1mm laminated Super Mumetal 250 and wound with 99.99% pure silver wire, which significantly increases manufacturing and material costs compared to copper. Each Transformer is then housed in a Mumetal screening canister to minimize noise and interference.
Its cost comes from the above, plus it is a hand-assembled, premium-grade audio component built with high-specification custom parts.
Go on then, spill the beans...
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S4 SUT plugged in, AN V silver cables from the ARM 2 and AN V silver cables onto the moving magnet (MM) phono stage on the OTO amplifier. Slightly visible is a green grounding cable running from the SUT to a plug on the OTO chassis. This ensures there is no hum, buzzing, or any interference; it's absolutely dead silent. S2 next to it makes it really easy to swap cables for comparison.
Firstly, a slight adjustment.....
For fairness sake, before playing records for comparison I checked the output of each SUT using a decibel meter and constant tone record. The S4 was outputting 5db more at my listening position, so I ensured after changing SUTs I adjusted the volume either up or down to compensate. All upcoming LPs are reviewed with the same volume.
The needle drops...
"Swing Era 1937-38 LP by Time Life Records," side 2, was the first up.
Without repeating myself from previous reviews, the difference was not subtle. About as subtle as a slap on the forehead. Instant difference. I felt louder, brighter, more sparkly, more vibrant.
This mono recording had now got that (overused phrase coming up) "live feeling".
I played the first track, then back to the S2. My setup made this a pretty swift change.
Play the track again. It felt like a popped balloon; the pianos and trumpet shrank back between the speakers. I'd moved from a front-row seat to somewhere in the middle of the auditorium. The track was perfectly pleasant, the copper S2 giving a lovely tone which I was used to, but........
Back to the S4. Suddenly I was back to the front, as every single instrument soared from the speakers in a perfectly defined space. I could "see" in my mind's eye the expert craft with which each instrument was played and feel how much the artists were enjoying entertaining me.
This was like the AN V interconnect on steroids, WOW, just WOW.
Next up was a well-played MONO LP by Shelly Manne & Co from the early 1940s. I know this very, very well using the S2, and it is a lovely, close sound, all between the speakers, but you really feel like you're in a Jazz club in the middle/back. Tonally, it's warm and inviting. I was very interested to see how the S4 would fare.
Instantly, I was pulled forward in the audience; the individual instruments, which before required concentration to separate, were now all clearly separated in their own spaces.
There was far more life and vitality, and I could now look at the instruments with my eyes shut and marvel at each of them before moving on to the next.
Instruments, especially the saxophones/clarinets, which had previously stayed broadly between the speakers, now climbed out to the ceiling and hung mid-air.
I was enthralled; one of my most enjoyed albums was now enjoying a new lease of life!
In the words of Monty Python, now for something completely different!
Charlotte de Witte Sanctum EP, 3-track 12" single (NOW available on eBay for £12.49 - bargain; I paid twice that...). It's minimal/acid techno, but each song layers sooo well, and of course the bass is very satisfying!!
On went the S2: track 1, Sanctum.
As I'm now used to it via the S2, the bass hits hard, and each instrument/sound is introduced individually over the rhythmic, hypnotic bass line. When Charlotte's singing enters the mix, it has that lovely, haunting air, slightly rounded but very attractive tone.
I found myself thinking, "This is excellent; I don't think the S4 can improve on it; this is just how I like it." Tapping my feet, nodding my head, I was really enjoying myself—such great music.
S4 on, volume equalized, arm lowered.
Oh.
My previous smugness evaporated. This was TOTALLY different. In a better way.
The bassline, which 2 minutes earlier had been a hard-hitting single note, I now observed to consist of not 1 but 3 overlapping sounds. Wow. It was an enjoyable process just to look into the bassline, its construction and how it progressed as the track developed.
When each new sound was introduced, I could follow its journey in space until it either stayed or decayed. Most remarkable was Charlotte's ethereal voice; it now gained a keen edge and soared, hovering midway between me and the speakers. It now sounded truly eerie, marvelous.
Interestingly, the S4, at the same volume as the S2 pressurised the room far better. I didn't need to reach for the volume control to really FEEL the music. SANCTUM was completely satisfying without being physically pummelled by bass.
What an experience! Onwards and upwards!
And again.....another £10 Ebay purchase, The World of Ballet Vol 3 (I have Vol 1 and 2 but this is the best)
I'm no music expert, but I would consider this an essential purchase; it's packed with fantastic, room-filling, hairs-on-the-back-of-the-neck stuff.
First off, side 2 Rossini: William Tell.
The difference, I'd say, was akin to waving a magic wand and instantly upgrading this £10 eBay purchase to a half-speed-mastered MOFI 180-gram, all-singing, all-dancing £100 super LP.
Darko Greguras' dynamic transfer (startling difference between soft and loud passages) was fully in force,
"the soldiers dance" swooped and dived, alternating between beautiful shimmering and forceful foot-tapping drumming.
It was a glorious live experience.
I have played this LP at least 2 dozen times in the last couple of months on the S2; however, the S4's substitution stripped out any confusion and muddy notes, replacing them with crystal-clear, precisely placed holographic performances.
The size of the hall became identifiable; I was bang at the front, best seat in the house, experiencing the LP mentally and physically. I was listening intently, then scared half to death, then thrilled by the soldiers' feet dancing.
My vinyl-based system, with the S4 in place and very ably conducted by the OTO PHONO SE Silver Signature 35th Anniversary, had now taken a vast leap forward in bringing me closer to the artist's intent, whether in studio or live recordings.
As you can see, Tilly is fully in favor of The World of Ballet vol 3, and in case you were wondering, this IS her impressed face.
Twix, my girl spaniel, is not usually allowed in the music room to avoid her enthusiastically squashing Tilly, so this is a rare treat.
A few more albums of completely different types of music the S4 sailed through and enhanced my enjoyment massively. I'll keep it short so you don't die of old age....
Tool and Rammstein: Yes, this system definitely does metal! Through the S4, the hard-hitting bass and shredding guitars were stripped back with far more definition and excitement. Of particular note was Till Lindemann's voice; it now leaped from the speakers with far more menace than before- just what the doctor ordered, fantastic!
Street Sounds from 1982/Kraftwerk: rap and electronic music now layered precisely in so much space, you look forward to the next instrument being introduced, peering into the 3D mix with rapt fascination.
Martin Denny - Primitiva / Thomas Dolby: I'd consider both solid purchases. I know them very well; however, the S4 raised the bar so high they felt like new albums remastered just for me. The beautiful plucked elastic bass guitar on side 2 of Thomas Dolby left me genuinely flabbergasted at its realism; I could see its shape in midair and feel its impact.
Conclusion...
I think it's no secret by now that the recent addition of silver components to my Level 2 Audio Note (UK) system has been something of a revelation. (AN V interconnect and S4 SUT).
I do not have a "bright" room (about in the middle with the clap test) due to its shape, and the silver components have really lifted the sound, adding huge dollops of life, vitality, and liveness (if that's a word). If you have a square, very reflective room with few absorbent furnishings, ISIS interconnect and a copper-based SUT may suit you instead. The tone of the copper really is very appealing to me.
£6400 is a LOT for a small, weighty item. HOWEVER, its inclusion in a £40K system raises the performance level of the system to such an extent that you could argue that it should be one of the first picks on the team sheet.
40K system without the S4 or 46K system with the S4, I would say it's more than a 6K sound difference.
If you are lucky enough to be hi-fi shopping at that level, you should seriously consider auditioning the S4, as it will be sorely missed when it winds its way back to Brighton.
In case you thought I'd forgotten...
Performance level system! The S4 breaches the guidelines, as it's level 4; it shouldn't work!
I was paying close attention to this over the last couple of months.
The S4 definitely DOES work, without doubt. I would say I'm no doubt not plumbing the depths of its capabilities; if you had an Audio Note (UK) level 3/4 system, you'd be even more staggered
The level 3 £3800 S3 SUT (which I've not heard) has copper cabling rather than silver and the same large, fully interleaved super mu-metal 250 core as the S4.
Marc Phillips from PT Audiophile (Review HERE) praised the S3, saying:
"The result was a quiet, confident musical presentation that continually astounded me while evading any possible criticism".
Perhaps the S3 would wow me; I'm sure it would. It fits perfectly into the performance-level system for me; there's only 1 problem...
I've heard the S4.
Very Highly Recommended.
What's in blog #13?
I'm off traveling!
To the Audiobarn, Old Harlow, Essex, early next month (link HERE) to listen to 3 Audio Note (UK) systems, levels 2, 3, and 4.
I'm planning to turn this into 3 blog posts, as there's going to be sooo much great material and photographs.
I absolutely can't wait; hope you are too. See you then, and Happy Listening!