The Ultrafide U4PRE Ultra Sigma Preamplifier is here at Tannoyista, and putting it together with the matching U500DC power amplifier brings both body and soul which just keeps getting better and better.
In 2023, I reviewed the Ultrafide Ultra Sigma U500DC power amplifier, which has been a wonderful addition to the Tannoyista system. Now the matching Ultrafide U4Pre preamplifier has arrived at Tannoyista, and, together, this ultra sigma combo is something that brings the true world of professional high-end audio into your own space.
If you've read my review of the Ultrafide U500DC power amplifier, you'll know that Ultrafide is based in Devon, UK, and is part of the MC² arm of the XTA group. MC² has had many years of experience developing professional audio equipment for recording studios worldwide since 1993. In fact, Abbey Road and Air Studios, to name just two, have been using MC² gear in there control rooms for quite some time.
Technically matching the U500DC, the U4PRE is Ultrafides first preamplifier, and, like the U500DC, it’s developed mainly for hi-Fi, but because of it’s versatility, it also straddles the line of semi-pro applications too.
The U4PRE is a pure analogue stereo preamplifier featuring an ultra-low-noise, configurable RIAA MM/MC phonograph stage. It has 5 stereo inputs and 4 stereo outputs, all of which are both balanced (XLR) and unbalanced (RCA).
And the versatility doesn’t end there; read on.
Unboxing the Ultrafide U4PRE:
The U4PRE weighs in at 6.5 kgs and has the same footprint as the U500DC. The box is identical to the matching U500DC and well designed to avoid transport damage.
Lifting the unit out of the box, you can immediately feel the quality of the unit. The ultra-solid build quality and weight are very pleasing.
The remote control is also very nice. Made from solid aluminium, it has a nice, solid weight, and the buttons are easy to press.
Initial look and feel:
Again, like the U500DC, the design is stylishly minimal and professional, which is nice. The construction of the case is beautifully executed using thick 3mm logo embossed alluminium and a beautiful textured black finish. In addition, the feet are also made of solid alluminium with rubber inserts.
The central screen is a colour OLED type, and both control knobs are made of solid aluminium. To the right is the power button, and to the left is a TRS-type headphone socket.
The U4PRE has been designed from the bottom up and brings some important and versatile features in sound adjustment, connection, and expansion choice options. It has quite a few features, which are very welcome to us audiophiles.
The right-hand rotary knob controls the volume, which is displayed as dB on the display. When the knob is briefly depressed, the input is muted. If kept depressed for a couple of seconds, it displays a menu with some very handy features.
The left-hand rotary control knob selects the inputs, and when kept depressed, it offers overall channel balance adjustment.
The U4PRE’s internal menu system is coherent and easy to use. Simply scroll through the options via the right hand control and it brings some very useful and very welcome control to any system.
Independent input gain adjustment:
Back in the dark ages, input gain was dictated at the factory or by placing horrible in-line attenuators in the signal path. The U4PRE, however, has an independent input gain adjustment, which is a very welcome feature and essential for any serious system.Getting the inputs to have a closer resemblance in volume to each other is something I’ve always struggled with. Due to the loudness war in the production of some material, sometimes, and rather annoyingly, the input on CD can be incredibly loud while the phono input can be almost whisper quiet.
So, that painful and panic-stricken dash for the volume knob and having to scrape your brains from the wall afterwards have gladly gone for good. The U4PRE allows you to adjust the gain on each line-in input independently to achieve a more respectful switch-over volume. Whether your device is connected via RCA or XLR, the gain can be reduced to suit by up to -10 dB.
The gain of the MM/MC phono stage can also be adjusted by +36 dB, (in addition to the
Independent input channel balance (L+R) and overall balance:
Personally, I’ve never had any need for this, but to change the balance per input as well as overall balance adjustment is quite unique and it may be very handy for some.Changing input title name:
Each of the inputs are named by default as just that: ‘INPUT 1’-2, 3, etc. So instead of trying to remember which input has what connected, this feature allows you to change each input title name to suit your chosen connected equipment.Connections of the U4PRE:
The connection panel is also made of thick aluminium, which gives a solid feel when connecting/unconnecting and has a plethora of inputs and outputs, reminding me of a pro-design, which is great to see.
Inputs and Outputs:
It has 4 line-in inputs, and it gives you the choice of using either XLR or RCA. The U4PRE also has quad outputs. It also has 4 outputs on both XLR and RCA to allow connection to multiple sets of monoblock amplifiers. At some point, I’d love to try it with this preamplifier.
All of the external balanced connections are impedance-matched and DC-coupled.
Connections
• 1 Stereo pair Phono inputs
• 2 Stereo pairs single-ended RCA inputs
• 2 Stereo pairs balanced XLR inputs
• 2 Stereo pairs of single-ended outputs (RCA)
• 2 Stereo pairs of balanced outputs (XLR)
All of the connectors are high-quality, gold-plated, and easy to get to.
System Triggers
System triggers are not commonly seen on Hi-Fi preamplifiers or power amplifiers these days. These are simple 3.5mm TRS jack sockets and you can use any kind of 3.5mm jack cable. The purpose of these is so that when you switch one unit on, the connected unit switches on too. The trigger is 12V for input and output. The trigger is a constant 12V on both ports for output triggering. This makes the U4PRE the parent in the system.The MM/MC Phono Stage
The phono stage is an ultra-low-noise, digitally controlled phono stage with an incredible dynamic range and an ultra-precise RIAA curve and recovery stage. The RIAA curve uses 1% tolerance parts, with individual stages for each turnover frequency.An inaudible elliptical anti-rumble filter is measured at >40dB of reduction @ 2-6Hz.
The phono stage inputs are on one side of the connection panel, away from the other inputs and outputs, and include a decent grounding post. Underneath the phono stage inputs is a bank of DIP switches, which allow you to adjust the load to suit your cartridge. For MM, its selectable from 100pF to 470pF in 8 steps, and for MC, its 85R to 500R in 7 steps, with the 8th being 47K.
With my Denon DL103C1 cartridge, a setting of 100R was dialed in via the DIP switches using a toothpick or cocktail stick. This was pretty easy to do.
A full table of gain and DIP switch settings for both MM and MC is available at the bottom of this page.
The gain for the phono stage can be changed via the right-hand control menu and is controlled in 30 x 3dB steps (+35dB to +71dB)
Another great thing about the U4PRE is that you can change the gain on-the-fly to fine-tune things if required. This also goes for all the other inputs too!
The Headphone amplifier
Many headphone amplifiers fall short of demanding users. But the U4PRE has much to boast about. The internal discrete, super-low distortion, high-damping factor headphone amplifier is a class A/B design and runs at 30 volts. It is capable of driving headphones from 8 to 300R (and even higher) and is optimised for 20 to 100R, which is nice.
D-Sub connector
It also includes a 9-pin d-sub socket, which includes balanced audio and power that can be used for other future equipment. Watch this space.The Technology of the U4PRE:
The U4PRE adopts the same Ultra Sigma technology as the matching U500DC power amplifier, which uses several high-performance NJR bipolar op amps in its signal path, and all are set up with their outputs re-biassed for class A operation.
Bringing in many years of experience with professional audio design, it uses extremely short signal paths for the lowest noise and distortion. So, with the U4PRE along with the U500DC, you get a unique Ultra Sigma pre/power combo that is second to none.
The system uses an over-engineered shielded linear power supply that has been specially developed to segregate mains and audio signals. The super-accurate volume control is analogue, and it has a dynamic range of >111dB.
Inside the U4PRE:
Switching on:
Like the matching U500DC, the U4PRE comes with a power switch at the rear of the unit. Once this is switched on, you can hear a few relays click into operation, and the unit goes into standby mode until the front power button is pressed or via the remote.
Upon power-up, the OLED screen fades up to show the Ultrafide logo before the volume status in dB is displayed.
With all of my kit, even the pro kit. I’ve always allowed time for it to warm up for at least an hour with no input signal. This ensures everything inside is ready to go. With this, I check for any noise from my loudspeakers. My speakers are quite sensitive, and with the Ultrafide U4PRE and the U500DC, all I get is an eerie silence, which is great.
The Sound of the U4PRE:
Connected to the U4PRE are my Trio L-07D (Trio L-07D Review) turntable with a Denon DL103C1 cartridge and, for digital, my Weiss DAC-204, using the classic Denon DN-961FA as a transport. I’ll also be using high-resolution SACD audio via the Weiss DAC via USB.
First, I’m going to start with digital using balanced connections and with the amplifier timbre set to pure. For more on this setting, please read my review of the Ultrafide U500DC Power Amplifier.
The Weiss DAC-204 (Weiss DAC-204 Review) is superb and, I believe, has a very nice synergy with the U4PRE. The first album was a classic. Paul Simon, Graceland. I’ve known this album since it came out around 1986, and it’s always been one of my favourites.
From the off, a striking presentation was fixed in place. The track, ‘Boy in the Bubble’, came through my 15” Tannoy Monitor Golds with a smooth and solid groove, and as the song progressed, I couldn’t help but smile.
Other tracks, such as Graceland, ‘Diamonds on the Souls of Her Shoes', and ‘Homeless’, were standout tunes. In these tracks, the amount of air and feeling is rich and dimensional, which the U4PRE pulled out with impressive ease.
My next album was The Stone Roses: Second Coming. Although their debut album is my absolute favourite, Second Coming brings back wonderful moments and not so great moments for me, so, overall, it’s an emotionally charged ride for me.
From the first track, ‘Breaking into Heaven’, the long, low ambient soundscape came through with amazing detail, while ‘Begging You’ and ‘Love Spreads’ really punches a hole through the sound stage. The fluid basslines and the clarity of the drums set the groove.
The amount of energy the U4PRE gives is something I believe will be impressive with any decent power amplifier, but for synergy, the U500DC really does bring that extra vibrancy to the picture.
Other noteworthy albums are Chemical Brothers: Come With Us and The Sisters of Mercy: Floodland.
Taking Floodland for a moment. The production of this album is second to none, and although my vinyl version sounds superior to the CD version, the U4PRE brought the sound through better than I’ve ever heard it before.
Moving on to DSD high-resolution music via my laptop. The result was even more impressive. The main thing that stood out was that the expanse of the stage was somehow wider. Led Zeppelin, Pink Floyd, and Queen, for example, sounded amazing.
I really like the SACD format, but some SACD titles aren’t so great, in my opinion. It sometimes seems that some mastering or remastering productions have failed to gain an advantage over redbook CD versions; some, it seems, have added false frequency emphasis, which makes them quite mediocre in comparison and, in my opinion, was done to probably boost marketing and justify the SACD HD format hype. Especially, it seems in the earlier titles.
But, thankfully, playing the titles I have is an improvement over my redbook counterparts, and I was indeed very impressed as the U4PRE handled them with total grace.
Using the internal MM/MC phono stage:
This is where my passion comes into its own. Internal phono stages on some equipment can be a bit uninspiring, okay, satisfactory, or not bad. So I approached the U4PRE’s internal stage with some very high hoops for it to jump through.
The updated Croft internal phono stage is excellent. But in this case, we have two very different beasts, as the Croft is purely valve-based. Can we do a direct A-B comparison? Not really. Valve has its own sound, and rolling a valve can sometimes change the sound to quite a degree, and it’s all about a preference for harmonics. Buying decent and true NOS valves is now becoming more difficult and expensive.
Valves have a type of distortion characteristic that gives a euphonic bed to the sound. This is something that many solid-state phono amps and preamps try to replicate and sometimes fail, making it sound over-egged and flattened, or stood on’ dynamically.
But, because I’m someone who has been using valve equipment for such a long time, that pure and unrestrained euphonic sound is what I’m looking for, or to just have some form of that would be something very impressive indeed.
So, what we can do is make a comparison in terms of how it brings that natural presentation, emotion, and resolution. And the aspect of fatigue, which can be the case with some solid-state phono preamps.
So, the U4PRE has its work cut out, has it not?
For this extensive test, I’ve been through most of my collection and pulled out the moments that really stood out. And, yes, it took a while. But believe me, it was worth it.
Starting with one of my all-time favourites for bass and dynamics. My first choice should give me a good overall measurement of how the phono stage performs. Hallucigen: In Dub. The amount of bass and dynamics on this album is really quite something. From the first needle drop, I was taken aback. Wow, this is good.
The first thing I noticed, as before, was the width and depth of the sound stage. It was vast. The amount of detail was also quite astonishing, with the bass being focused, precise, and not overblown.
When you sit down and wait for the music to start, if the music begins gradually, it’s great when something emerges from that inky blackness. The whispered details start to pop through, building dynamics once you’re up to speed, and its at that point when harmonics are available to judge. In this case, my judgement was simply startling.
Moving on through some other vinyl. Another standout album was Curtis Mayfield, Curtis. Remastered by Bernie Grundman, this album is now over 50 years old, but what an album it is. I really love Curtis Mayfield, and I was very pleased to hear it come through with such grace.
Although the recordings of Curtis were never top-notch, it really doesn’t matter. They still sound better than a lot of productions today. This, for me, is the high watermark for soul/R&B, and as it should be, raw, a little rough around the edges, but with huge talent, unlike most of today's cookie-cut bedroom versions of the genres.
With a wonderful textureble landscape, the U4PRE, together with the U500DC, exercised this album with total respect; separation was right up there without it sounding harsh. Could I comfortably place a reference to a live performance quality in this? Yes, absolutely, bringing a fluid, organic ease to reproduction.
The same went for Curtis’s other albums. A wonderful soundstage, an inky silent background, and a fully natural definition. Another great listen was Scientist, ‘The Best Dub Album in the World’. Wow, what a treat. Deep bass, snappy drum echoes. You can’t fault the reproduction. Then came Seals debut album. Amazingly easy to listen to in parts with that 3D ambiance soundscape. It’s quite something.
With the U4PRE, I felt that I was listening to something refined and pure. The clarity came through with a natural wash of ease.
Conclusion:
How does it stack up to a well-thought-out valve preamplifier on both the line stage and the phono stage? Well, it stacks up exceedingly well and is, in fact, preferable in comparison. This is by far the best solid-state internal preamplifier I’ve heard yet.
Why? Well, for a pure solid-state preamplifier, there are small traits of a valve-like sound with a beautiful openness and accuracy, which was really nice and surprising to hear. With a non-fatiguing, effervescent characteristic to the sound, it’s not overblown or stood-on but simply open and expressive. It gives a fresh, solid, and focused presentation with a very refined and velvety touch, which was very surprising and very welcome.
Its presentation is smooth and dynamic, with resolution and space having a clean and natural presentation in which to wallow. At the same time, the sound stage is wide and deep, with uncanny ways of separation and air. Something that is a rare gift these days.
Together with the U500DC, there's a wonderful synergy, which you’d expect, and with that, it clicks together that studio live sound with amazing ease. You get a great sense of involvement and refinement, as well as a beautiful bloom of sound. But, as I mentioned earlier, this preamplifier is very versatile, and I can also see the U4PRE matching any decent valve amplifier too. It certainly has that knack about it, which would click very well with either an EL-34, KT-88, or KT-120/150 power amplifier.
And, just stepping away from the sound for a moment, we can’t forget the build quality, the design, and the flexibility of this preamplifier. You just can’t fault it. For the serious audiophile, it’s quite wonderful and liberating to have that freedom to connect and change so many aspects of a preamplifier to suit your system.
The U4PRE is mega quiet and very engaging, and it Sits perfectly at the price point of £4500. What you get here is a whole chunk of experience within audio. Nothing about it is strained or rushed, and Ultrafide has done a wonderful job in every respect.
To close. The U4PRE threw nothing at me that I didn’t want to hear, and everything I did. It surprised me more than I expected. From digital to analogue, high-resolution audio to vintage vinyl, the Ultrafide U4PRE revealed that if the power amplifier is considered the heart, then the pre-amplifier is most definitely the soul.
Putting both the U4PRE and U500DC together, you get the very essence of a phenomenally explosive and powerful sounding combo of sonic magnitude.
Product Details:
U4PRE Preamplifier:
Ultrafide Audio by MC2 Audio
XTA Electronics Ltd - Trading as MC2 Audio & Ultrafide Audio
Units 6-7 Kingsgate
Heathpark Industrial Estate, Honiton, Devon
EX14 1YG,
Tel: +44(0)1404 44633
Email: hello@ultrafideaudio.co.uk
Website: www.ultrafideaudio.co.uk
- 5 Year Warranty
- Quad outputs for use with bi-amplified system
- Class A circuits
- Minimum Signal path
- DC (and Super Low Frequency) Coupled Systems
- Premium headphone amplifier
- Highly configurable ultra-premium phono stage: suitable for use with a wide range of moving magnet and moving coil cartridges
- OLED screen with remote control for full configuration
- Expansion port for additional interfaces
- Over engineered power supply
Specifications:
Default Additional Gain Result Application
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