The Article

HFSA-01 INTEGRATED AMPLIFIER FROM AURORASOUND

17th April 2024

Sporting a distinct retro aesthetic, Paul Rigby reviews this Japanese-sourced, hybrid, integrated amplifier

The HFSA-01, from Japanese outfit, Aurorasound, is a hybrid amplifier that features a solid state pre-amplifier module and a valve-based power amplifier linked via a phase invertor. Which is, in itself, intriguing because most hybrids that I have run across reverse that process. I am interested to hear how that design decision will translate into sound.

Four ultra linear, push pull EL84s provide a 14W per channel power output. So right there, you need to decide just what system your running and if this power offering is enough to drive your system. Saying that, I have sometimes been surprised at just how powerful such a low-wattage amplifier can produce, especially if it has been efficiently designed. So again, let’s see how that pans out in the sound quality tests.

Rectification is provided by a Rhom silicon carbide which, says the company, offers very low noise in operation.

On tour now and around the back of the chassis we have connections for a built-in phono amplifier plus grounding grub screw, three single-ended inputs, speaker binding posts for both 8 Ohm and 4 Ohm speakers and, to the right of those, an IEC power socket.

On the front are rotary bass and treble tone controls that I personally dislike. I see them as a waste of build budget that, on am amplifier of this price, could have been used to build better parts. How about a MC option for that phono amplifier for example? Or even to lower the price of the amplifier itself?

Saying that though, what I do like about these tone control knobs is when they are not. That is, when using the internal phono amplifier, they act as a source of alternative EQ curves for older vinyl. Pre-RIAA, you might say. This is an excellent addition and, in my experience unique. Aurorasound even provide a plate that you can add to select the EQ for you.

There’s also rotary knobs for volume and the sources. Below and to the left is a push button power button, tone and direct buttons (I kept this on direct throughout the review), a useful stereo and mono switch (especially so considering the supplied alternative EQ curves) and a 6.35mm headphone port. And I approve of the size of the headphone socket on an amplifier of this price point. That headphone amplifier is powered by a separate Op Amp, not the power amplifier section of this unit. So again, it’ll be interesting got hear if the personality of the had amp is the same as an amplifier as a whole.

So how does this box actually sound? Let’s nip over to the Sound Quality tests and find out.

SOUND QUALITY

I began with CD and Ennio Morricone and the original soundtrack album Ecce Homo – i sopravvissuti (thats Ekke Homo because, you know me , I always take the classical Latin approach to life)

Underneath the amplifier chassis

This one was released in 1969 for the film of the same name. This CD was released in 2002 on Dagored. It’s quite a sparse, avant arrangement, of orchestral wind and string instruments which is of great use while testing HiFi. The music offers orchestral punctuation, you might say plus the odd vocalisation. It’s…challenging. Put it this way, you won’t find it being played at your sister’s wedding. There’s no Dad dancing off the back of this one.

First impression from this amplifier? It offers an efficient design. That 14W output? Surprisingly, more than enough to drive my reference system and I was running low sensitivity Quad 57 electrostatics. Yes, I did have to up the gain which was no surprise but saying that, this amplifier never felt strained or under powered during my tests.

With EQ plate added to the tone controls

Next? Focus. There’s tremendous focus from the HFSA-01. I’m used to a bombastic, sprawling bass from my reference amplifier but not here. The HFSA-01 tuned bass to be compact, full of impact sure but neat, tidy, still powerful but also lean. The bass from this track also trailed lots of reverb. That was here too via the HFSA-01 but the lightness of that reverb contrasted well with the meaty bass.

Female vocalisations from this album were also precise and disciplined. And that was something else from the HFSA-01. All frequencies were disciplined. This album promotes frequency chaos. It’s so easy for an amplifier to overdo it to move beyond the boundaries so that mids are ragged and bass a little boomy but not here. Frequencies were tight, honed and condensed. That, in itself, allows the music to increase its pace. It never dragged.

I then challenged this amplifier with a tale of passion from the punk band Serious Drinking and the footballing tale of passion, Love on the Terraces from the vinyl album, The Revolution Begins at Closing Time. I also noticed a pair of Martin Logan 15i speakers nearby which offered a higher sensitivity figure which meant, of course, that less gain was required from the HFSA-01. So I hooked those up to my HiFi chain. Hence, the amplifier didn’t have to try nearly as hard to find the same volume level.

Sorting out the crashing arrangement from this album is a challenge for any amplifier but the HFSA-01 did a superb job, adding a sense of order to the band itself while improving the vocal diction and delivery. The low noise around the mids certainly helped on that score.

I then plugged in a pair of Sennheiser HD600s to access the built-in headphone amplifier. The general sonic envelope is similar to the speaker output although the headphone amplifier is, if anything, cleaner, stripped and sparse around the mids with enough bass to keep the pace of the music high but the overall sound is not quite as rich as the speaker output.

As for the built in phono amplifier, I connected a Rega RP3 to that very module and played the same Serious Drinking LP. And I have to say I was surprised at the quality of this built in phono amplifier. Clarity around the upper mids was there, there was enough bass to form a solid foundation for the track as a whole while there was plenty of details keep you engaged. One of the best internal phono amplifiers I’ve heard for some time.

CONCLUSION

I was impressed by the Aurorasound HFSA-01 integrated hybrid amplifier. I loved the retro looks, I liked the solid feel, the practical interface and while I wasn’t enamoured by the tone controls I loved the quirky vinyl EQ tools. More than any of that though I was impressed with the focused, lean and clean, low noise sound.

AURORASOUND HFSA-01 INTEGRATED AMPLIFIER

Price: £3,699

Contact: [email protected] or buy via phone on 07551 955775

GOOD: low noise, focused bass, precise and detailed mids, retro aesthetics

BAD: tone controls