HSE Masterline 7

REVIEW
Alan Sircom
Mar 20, 2025

Founded in Switzerland by ex-Studer legend Robert Huber in 1987, HSE makes a small but extraordinary range of audio electronics, of which the Masterline 7 phono preamplifier is arguably the most famous. HSE (or HSE Audio, or even HSE Swiss: names are not important when you are this far up the mountain) used to make both professional and domestic equipment, and the company’s EQ1 four-band parametric equaliser and M4000 microphone preamp for SSL 4000 desks are still highly prized among well-heeled studio owners, engineers and producers.

HSE still makes pro audio equipment to order, but the lessons learned in making uncompromising equalisers for studio use could be ported into making uncompromising phono equalisers for home use. The rest is solidly built history, albeit a history that is 24-carat gold plated in its most important areas.

A small range

The company is not one to flesh out its line with dozens of products. It’s a small range of ultra-fi. Alongside the Masterline 7 (or ML-7), there’s a matching Masterline 8 line preamplifier (which lists a Weiss DAC as one of its available options; such is the degree of finesse we are at here). There is also a Referenceline 7 two-box, dual mono phono preamp for those whose criteria – or bank balance – doesn’t quite reach the peak of the ML-7.

There is also a variant of the HSE ML-7 called the Masterline 7 VAREQ. Either specified as the ML-7 is built for you or available as an upgrade (for a premium), VAREQ gives you control over EQ curves other than RIAA. The four controls for these EQ settings are built into the top panel of the phono stage.

More than switch-flipping

As the name suggests, this is more than simply flipping a switch from ‘RIAA’ to ‘Decca’. There are 12 settings for roll-off (the amount of damping at 10kHz) and the turnover frequency for the high-pass filter. The 16dB and 500Hz settings for the RIAA curve are highlighted in red on the four rotary controls.

However, the model tested was the standard HSE Masterline 7, and it’s said that the RIAA-only version outsells the VAREQ curve model by about 5:1. Doubtless, people who want to shout about the importance of additional EQ curves (or lack thereof) will have something to say about this, and will likely say it loud, but that ratio says a lot.

There is an additional option. The existing external AC70 power supply can be boosted to the AC300. As the name suggests, this adds 300VA of additional toroidal transformer ‘beef’ alongside the line DC filter and soft start (inrush limiter) found in the standard AC70. This can be used with all three Masterline products.

Necessary complexity

The phono preamplifier has 37 different gain settings, 24 impedance settings and 12 capacitance settings, although these are set to match popular cartridge designs like Ortofon, Lyra, and ZYX. The ML-7 can be built with higher gain on request if you are trying to link the HSE phono preamplifier to some impossi-load (such as some of the Audio Note Io models). As this is a truly dual mono design, these settings are not ‘commoned’ so you have to set them individually on each channel.

However, far from being unnecessarily obtuse, this is a necessary complexity in action. At this level, the phono stage is so precise that tiny differences in cartridge coil winding between the left and right channels can be resolved, and small variations between the left and right settings are more than just fine-tuning. There are also those purists who will use the gain setting as a volume control and do without a preamp. They can gain-ride the central VU meters like a boss. I don’t think turning those two gain knobs like a safe cracker while playing a record does it for me, but your mileage may vary.

Not scratching the surface

We’ve barely scratched the – beautifully made – surface of the HSE Masterline 7. The three balanced-only XLR inputs are built to a high grade and matched by the single XLR output per channel. All have an independent ground-lift switch at the rear in case of hum loops. Eight mini-toggle switches on the front panel control everything from the choice of input through activating the passive 15Hz subsonic filter to the brightness and scale of the VU meters.

HSE VU meters

If the connections and controls are comprehensive, the internals take it to a new level. The HSE ML-7 has an Equivalent Input Noise of -144dB across the frequency range. EIN is a figure used in the pro-world to determine the noise of a microphone preamp. In phono preamp terms, the HSE is quieter than the noise floor of many good DACs. This was easy to demonstrate. It was unbelievably quiet.

The HSE Masterline 7 features twelve discrete Class A gain stages and two low-noise zero-ohm Class A head amplifiers. Built to last (HSE claims at least a 30-year life expectancy), the phono preamp is built into a milled-from-solid aluminium block with 20mm thick walls. This not only makes the ML-7 free from any transmitted vibration, but it also aids EMC shielding. The ML-7 sits on its own ‘Vibfree’ support platform.

Hand made

It’s all built using the highest quality hand-made Swiss components, and the Bill Of Materials reads like a Who’s Who of audiophile top-grade components: ELMA, Goldpoint, NKK, Panasonic, WIMA, Neutrik, and Schurter, as well as HSE Audio self-wrapped coils are used. All these electronic components are hand-selected to an impossibly tight 0.2% tolerance. Even the internal wiring is the patented silver-Teflon wiring developed by HSE. Finally, the heavy toroidal transformer in the external power supply chassis has the best static and magnetic shielding.

HSE says the ML-7 is “When highest Swiss quality engineering meets Italian design.” The champagne gold front panel with 24-carat gold knobs and details, the two central VU meters and overall styling are not one for ‘understatement’ as befits the country that bought us the Ferrari SF90 Stradale, but in the flesh, it has a timeless elegance that is hard to get from the pictures. It’s no shrinking violet, but neither is it garish.

A phono preamp of this gravitas and resolution isn’t going to be used with an entry-level Rega or Pro-Ject, but the ML-7 doesn’t automatically require ‘back of the wine list’ products. It should be ‘intelligently’ – and not simply ‘expensively’ – partnered. For example, it’s surprising – and probably completely academic – just how much music you can get from a good upper middle tier cartridge costing about £5k when it’s used a £70k phono preamplifier.

Imposter syndrome

I’m dancing around the sound quality for a reason. I’m thoroughly lost here. Not just lost; lost in music. The HSE Masterline 7 is beyond what I thought possible from LP, and I feel like I have a bad dose of Imposter Syndrome. I may be close to hitting my two millionth word written about audio, but I need someone who’s done more audio reviews than me to finish my sentences here. This one is above my pay grade… Figuratively and literally.

Take ‘Murmuration’ from Go Go Penguin’s V2.0 album [Gondwana]. I’m used to the extremely fast and detailed drum work, often blurring to the point where it almost sounds better in a digital format. But here, that extremely detailed drum work was super-fast, coming out of absolute silence and extremely dynamic and precise. It also conveyed the excitement of a first listen and the track’s energy.

It’s almost academic pulling out different types of music to describe the HSE Masterline 7 because it’s so far ahead of the pack. But the two towers upon which high-end audio was originally built – classical and jazz – are played with gusto and passion here. There is so much information on tap that you almost absorb the liner notes of an album through osmosis. But the ML-7 is so revealing that you hear different musicians’ individual playing styles, and not necessarily on instruments you know well. It’s easy to pick out the playing style of Ray Brown on This One’s for Blanton! [Pablo] but it’s just as easy to pick out how carefully he’s channelling the playing style of the late Jimmie Blanton, which rarely comes through.

Classical dynamism

Similarly, in classical pieces like the Maazel/Vienna Phil rendition of Tchaikovsky Symphony No 4 [Decca], the dynamism and flow of the music are perfectly played. Around this time, the HSE makes you wonder if we didn’t take an almighty wrong turn in choosing a digital audio future. Classical listeners were the first to adopt CDs because of the absence of surface noise; they might be shocked at how much music they get playing, even crispy records from the 1960s, and how much of that music never makes it to digital. This astonishing phono stage brings out so much information in all aspects that your normal vocabulary is suspended.

I could play Duke Ellington back-to-back with Taylor Swift and Niels Frahm up against Willy DeVille. Each record was perfectly rendered, sometimes small and close-knit, other times expansive and energetic.

You want it darker?

The music got dark with Frahm and brightened up fast with Taylor Swift. This last wasn’t the best recording, but the HSE ML-7 makes the best of a bad job, and ‘Anti-Hero’ is enjoyably punchy, if way too close mic’d.

A record that doesn’t get played too often anymore is the 12” Annihilation mix of Frankie Goes To Hollywood’s ‘Two Tribes’ [ZTT]. But in so many ways, this track is telling and – sadly – probably just as relevant today as it was in the mid-1980s. First, it’s as dynamic as it gets and shuts down lesser mortal phono preamps. Let it rip here, playing at ear-shredding club levels if your system can take it. It also makes you wonder how much of that mix Trevor Horn heard in the studio and if he knows how much is on record. Because until I heard it through the HSE Masterlevel 7 phono preamplifier, I had only guessed. For example, there’s a double-tracked tom-tom mid-way through the ‘Condemn me!’ part of the mix that is inaudible elsewhere and clear as day here.

Unexpected volume

Playing this 12” showed the only issue with the HSE ML-7. We so associate phono stages with self-noise and background hiss that – when there isn’t any – we are unprepared for the volume we get. From the quiet of the run-in groove, I set the level higher than expected, and when that air-raid siren kicked in at the opening of the track, it was loud enough to send people nearby running for long-gone bomb shelters in panic. Fortunately, this was at the end of a listening session, so I could give my ears a well-needed rest.

I’m in awe of what the HSE Masterline 7 can do with your recordings. The absence of noise is remarkable, but it’s backed up by reproduction that moulds itself to the record playing. It’s as detailed, spacious, or rhythmic as the LP allows. You feel like you are listening to your albums anew, and the feeling is sublime. The HSE Masterline 7 might cost a lot of money, but you get a significant amount of phono stage in return. Wow!