The Hovland STRATOS Mono-Bloc Amplifiers

The notion that (in hi-fi terms at least) real power comes with a heavy cost attached had become something of an article of faith around these particular parts, not least because the sonic price paid all too often seemed even greater than the financial one. For many years, any amplifier offering much more than a hundred or so Watts seemed to become increasingly bludgeoning and muscle bound as its power rating climbed, reason enough to seek out speakers that offer a less demanding load. But then came the Karan KA M1200s, massive and massively impractical, there was no escaping the fact that, faced with the awkward load and extended bandwidth presented by Avalon’s Eidolon Diamond they were both much more capable and more musical than lower powered alternatives. Well, you can always stick a finger in the dyke of dogma, but when the latest range of conrad-johnson amplifiers gave the rare opportunity to compare genuinely similar designs at three different power levels, the intellectual temptation was simply overpowering. The result merely confirmed the suspicion raised by the Karans that it’s not the quantity that’s the problem, its executing its delivery, the LPM275s offering up a truly memorable performance.

appliqué Perspex slabs that create nonresonant sub-assemblies. The heavy cylindrical feet shroud adjustable cones to ensure stable placement and mechanical grounding of the amplifier’s substantial 40.5kg bulk. The shoulders can be replaced with extensions allowing the amps to be stacked, although sonically speaking I’d avoid this in all except the direst situations, as the uprights lack the sophisticated mechanical coupling of the chassis itself, thus negating its effectiveness. Having said that, they sure do look purdy…

Inside, these amps are beautifully constructed. The mains transformer is a sophisticated quasi-C core design which like the one in the RADIA is physically decoupled from the chassis, but unlike the relative simplicity of the arrangements in the stereo amp, here the transformer is both fully suspended and enclosed in its own separate housing to completely isolate mechanical noise and vibration. Metalbodied, bi-polar output devices are close coupled to massive internal heatsinks, in turn arranged to mechanically damp the transistors and cool them via the efficient natural convection currents created by the chassis’ chimney vents. With 80000 microF of reservoir capacitance provided by a bank of highspeed, slit-foil capacitors, the amplifiers’ agility and dynamic response is further enhanced by ultra-short signal paths.

Of course, this wouldn’t be a Hovland product without the signature blue illumination and the STRATOS doesn’t disappoint, the curved fascia edge lit by a wash of light. However, like all the other Hovland designs the light show can be switched off, leaving only the central blue line that acts as both standby and full power indicator. A switch on the back allows the user to select “low” or “high” standby modes, the latter running the audio circuits at idle but with the signal and speaker relays open, significantly shortening the time the amp takes to reach full performance. Also like the other designs, the STRATOS sound noticeably better in “stealth” mode with their illumination switched off. The results (the removal of a haze that in turn creates greater transparency and delicacy, and more effective phrasing) are so obvious that I wonder that anyone would actually use the amps “fully lit” – although it’s easy enough to switch on the lights if you are not listening and just like their look. In line with their functional elegance, the review pair were delivered in a simple brushed aluminium finish, although black is also available with matching black chrome trim. And while we’re on the subject of appearance let’s be clear about one thing: proportionally speaking, this is the most satisfying Hovland yet – and that’s saying something!

Where the STRATOS do differ from the RADIA, is in providing a choice of balanced or single-ended inputs (the stereo chassis must be specced as one or the other) and two-pairs of binding posts per channel (which only accept spades, but at least do so really securely without resorting to a socket wrench). This reflects in part the fully balanced topology employed in both this amp and the RADIA, but also the development of a sophisticated new active circuit to enable the single-ended input to properly drive the balanced amplifier, a circuit which is bypassed with the balanced connection. Although the HP200 pre-amp is now equipped with balanced outputs (using the inverse version of the STRATOS input circuit) and was supplied in this form along with the amps, a fully differential pre-amp and hard-disc derived digital front-end that match the look of the STRATOS were shown at this year’s CES. I used the amps in both modes, driven from either my Connoisseur line-stage, the Ayre K1-xe or the HP200 pre-amp. Cabling was Nordost Odin or Hovland’s own, while support was provided by finite-elemente platforms. One especially nice touch is that the large cylindrical feet and their associated cones are designed to allow easy replacement of the latter with an alternative should owners so decide. Those supplied are Black Diamond Racing cones, but the threaded studs that attach them will readily accept the likes of a Symposium RollerBlock without disturbing the appearance of the amps or leaving them looking perched on some sort of afterthought. I tried both the Rollerblocks and Stillpoints cones and the latter represent a significant improvement, providing enough extra presence, body and harmonic texture, as well as allowing Meanwhile, recent developments in loudspeaker design, most notably the Eidolon’s bigger brother the Isis, have made a genuinely powerful amplifier of real musical merit (and one that you might actually be able to pick up and move by oneself) an even more desirable (for a reviewer read “essential”) commodity.