Synthesis Roma 753AC Integrated Amplifier Review

Posted on 14th May, 2024

Synthesis Roma 753AC Integrated Amplifier Review

John Pickford auditions a charismatic Italian integrated amplifier, ably powered by thermionic valves…

Synthesis Art in Music

Roma 753AC Integrated Amplifier

£3,999

Synthesis Roma 753AC Review

Synthesis, or rather, Synthesis Art in Music to give the company its full title, was founded by Luigi Lorenzon in 1992. However, its roots can be traced back to 1961, when his father began manufacturing transformers for valve amplifiers. One of Lorenzon senior's output transformer designs was used in the legendary Vox AC30 guitar amp. The company offers three ranges, namely the Roma and the more expensive Action and Metropolis lines, as well as a flagship single-ended 300B amp.

UP CLOSE

The 753AC on test sits in the middle of the Roma range of stereo integrated amplifiers, between the entry-level 96DC+ and the top-of-the-range 510AC. It's a line-level design with five inputs, producing 50 watts of push-pull pentode power per channel, each making use of a pair of ECC82 (12AU7) input/driver valves and a pair of EL34 (6CA7) output valves – or 'power tubes' in the company's vernacular. Synthesis says that all tubes are selected after a two-stage warm-up, with a computer-monitored machine controlling the process as it “selects the perfect tubes which are then matched for a perfect balance”. So, optimally matched valve pairs are very much the order of the day here.

Synthesis Roma 753AC Review

No shrinking violet, for sure. The Roma 753AC is a large, heavy amplifier, measuring 235x410x503mm (HxWxD) and weighing 25kg. The power supply and iron-silicon output transformers are hidden from view and protected by “an extremely rigid structure,” which is designed to prevent unwanted vibrations and reduce noise to the valves. Floor-bound vibrations are further minimised by four aluminium feet with an insert of strong rubber at the base of the unit.

Visually, the Synthesis looks like it means business, with the four EL34s standing proud against a metallic silver back/base plate. Meanwhile, the smaller ECC82s are around fifty percent visible, poking up from holes in the base of the unit. Talking of holes, there are twelve of them surrounding each EL34, though whether these have any effect on sound quality or cooling or are purely cosmetic is not stated. Either way, it contributes to the product's purposeful, slightly industrial look. For those not seduced visually by the warm glow of valves, a removable cage is provided, which also performs as a safety device to prevent the burning of inquisitive hands or paws.

Synthesis Roma 753AC Review

Five front panel finishes are available, with our review sample featuring the black wood option; red and dark wood or black aluminium and silver are your alternatives. A large volume pot is situated centrally and almost flush on the front panel, with a fingertip-sized indentation encouraging single-digit operation of the volume control. However, many users will choose to use the lovely infrared remote control for volume adjustment (including mute) and source selection. Housed in an anodised black aluminium case and weighing 200g, it echoes the bomb-proof build of this amplifier.

For non-remote selection of sources, there are five push-buttons on the front panel, each with its own LED that illuminates when selected. A power switch and remote sensor complete the front panel feature array. On the rear panel, there are five pairs of gold-plated ceramic sockets for each line-level RCA input, along with gold-plated binding posts for speaker cables terminated with banana plugs, spades or plain old bare wire, if you prefer. A fused IEC power inlet socket is also situated here.

THE LISTENING

Like almost all valve amplifiers, the Roma 753AC's magic is in the midrange – by which I mean the middle band, where much of the musical action takes place. Here, this amp shows off its tonal vibrancy, faithfully reproducing the natural sound of voices and well-recorded acoustic instruments without adding euphonic colour in the style of some classic valve amps. There's never a sense that you're hearing a sugar-coated view of the music with too much syrup. Nor, thankfully, do you get the tonally grey and homogenised sound of poorly designed transistor amps.

Synthesis Roma 753AC Review

Instead, the midrange is infused with impressive focus, resolution and transparency, allowing music to flow freely with supreme neutrality. This is the area in which valve amps generally – and the Roma in particular – excel. The absence of solid-state grain and hash makes for a convincing real-world listening experience, with voices and instruments reproduced with their own unique tonality.

Upper frequencies are effortlessly reproduced without any of the hard-edged artefacts less capable designs have a tendency to show. Cymbals, for example, never come across as shrill, clanky or overly splashy. Listening to Miles Davis' Miles Smiles, which is one of the better-recorded jazz albums from the mid-1960s, and the cymbal work of drummer Tony Williams propels the tune with the authentic timbre of wood-striking-copper, along with all the accompanying overtones that you hear in a live situation. On the album opener Orbits, the trumpet and saxophone play the main theme in unison. Yet, the tone and expression of each instrument remain well-defined rather than coming across as an indistinct mush.

Synthesis Roma 753AC Review

While the timbral accuracy and resolution of the Roma are as good as I'd hope for from a well-designed valve amp, its dynamic expressiveness goes way beyond what I've come to expect from the breed. Mike Westbrook's Celebration, a big-band British jazz album from the same year as Miles Smiles (i.e. 1967), features dramatic dynamic swings, with solo horns giving way to full-band blasts in an instant. I've heard valve amps buckle when asked to express such explosive dynamics, yet there's never a sense of the Roma running out of musical power or momentum.

It is fortunate that my time with this amp coincided with my musical reappraisal of Led Zeppelin. While they were at the forefront of the late nineteen sixties and early seventies heavy rock genre, the band covered a wide variety of musical styles, sometimes within a single track. A case in point is Over The Hills and Far Away from Houses of the Holy. Here, the opening solo acoustic guitar is replayed with stunningly rich harmonic definition and texture; however, when the band kicks in, nothing is lost in terms of clarity and musical separation, and there's a tangible sense of dynamic power and drive. Thunderous drums and biting, overdriven electric guitars give way to soft, distantly recorded guitars and synths drenched in reverb without losing focus and transparency. Scintillating stuff from the Synthesis.

Synthesis Roma 753AC Review

Playing a varied menu of rock and jazz, it is clear that while the Roma's bottom end is full, weighty and deep, it could be more fast and firm. That's not to say the amp is saggy, sloppy or vague – far from it – however, those who prioritise pace, rhythm and timing above all else may find it lacks the 'boogie factor' they hold dear. If you were trying to persuade a Naim devotee to try thermionic power, this isn't the amp to show them. Similarly, a valve purist smitten by their 7 watt amp that makes everything slightly toffee-flavoured will likely find the more forthright nature of the Roma hard to swallow. The truth hurts, as they say.

THE VERDICT

The Synthesis Roma 753AC is a no-nonsense, line-level integrated amplifier – although, of course, this depends on whether or not you consider certain features to be nonsense. For example, few audiophiles will bemoan the absence of tone controls or even balance adjustment; in the same way, most wouldn't welcome a loudness button or VU meters.

Yet if, like me, you are a vinyl junkie, the absence of a phono stage might be a turn-off unless you already own one or prefer the idea of buying a standalone phono preamp, such as the Synthesis Roma 79DC Phono Preamplifier. The upside to this is that if you're not a lover of the traditional plastic wax, none of the Roma's asking price is wasted on a superfluous stage of amplification.

The same could be said for the lack of headphone compatibility, but this would be a deal breaker for me. While dedicated headphone amplifiers are available (not within the Roma range, although the 117DC Preamplifier has a headphone output), much of the appeal of integrated amps, as opposed to pre/power separates, is having everything you need in one box.

Sonically, the Roma 753AC has an awful lot to offer, especially in its tonally rich midrange and its ability to react to sudden dynamic shifts. Those who romanticise the rose-tinted presentation of low-powered single-ended valve amps might find its timbral accuracy fails to satisfy their sweet tooth. Those who demand grip and grunt above all else might feel this amp is a little loose in the low end. If, however, you are looking for a seriously capable all-round integrated valve amplifier, this charismatic Italian is well worth auditioning.

Visit Synthesis for more information

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    John Pickford's avatar

    John Pickford

    A professional recording engineer since 1985, John strives for the ultimate in sound quality both in the studio and at home. With a passion for vintage equipment, as well as cutting edge technology, he has written for various British hi-fi and pro-audio magazines over the years.

    Posted in:Hi-Fi Amplifiers Integrated Amplifiers Applause Awards 2024
    Tags: synthesis  henley audio 

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