Pre/Power Amplifiers

The best of both worlds' is an oft-used rallying cry in the hi-fi industry, rolled out to extol the virtues of everything from compact loudspeakers with big bass output to digital network players with phono stage inputs. It's also the self-proclaimed raison d'être of PS Audio's Stellar M1200 monoblock amp. Sold in pairs for £6000, this recent addition to the Stellar range combines a high-power Class D output stage with Class A vacuum tube input, in pursuit of both efficient speaker-driving muscle and spine-tingling musicality.

It certainly appears up to the challenge of providing sufficient grunt. The claim here is of a 'minimum' 600W/8ohm and 1200W/4ohm – figures not typically found at the price. This is more juice than you're ever likely to need, but the Colorado-based brand claims it is fundamental to the amplifier's appeal: 'The over-the-top high power output of the M1200 exists not to match a small handful of power-hungry speakers, but, rather, to act as the perfect uncompressed power source for even the smallest, most efficient of speakers on the market'.

Getting Into Stellar
The Stellar series is PS Audio's entry-level, launched in 2017 with the £1350 S300 stereo power amplifier, £1550 Gain Cell DAC/preamp and £2700 per pair M700 monoblocks [HFN Apr '20] followed more recently by the £3000 Stella Strata integrated, £2500 Stellar Phono Preamp [HFN Feb '20] and the M1200 here.

What differentiates the M1200 from its more affordable monoblock stablemate is not just the promise of additional power – the M700 is rated at a 'mere' 350W/8ohm – but its hybrid design. So, while the M700 features the brand's 'Analog Cell' technology, which it describes as a 'Class A MOSFET input stage [that] closely mirrors the sonic characteristics of a vacuum tube', here you have the real thing – a 12AU7 triode fed by its own power supply.

A hybrid amplifier architecture also features within PS Audio's flagship BHK series of mono and stereo models [HFN Jul '16] though these are a mix of tubes and power MOSFETS. The tube/Class D blend of the M1200 is distinctive and described as a 'dream project' by lead designer Darren Myers. The chosen Class D power module is an upgrade over the M700, using ICEpower's latest 'Edge' circuit design to enable a more predictable response/distortion behaviour regardless of loudspeaker load.

Otherwise, the M1200's styling follows the trend set by other components in the Stellar range. Indeed, the amplifier looks almost identical to the M700. The chassis is the same width (432mm), and while a shade taller it's slender enough to make placement simple, the two easily stacked and placed on a shelf or in a cabinet.

Playing It Cool
The Class D design informs its form factor: there are no razor-sharp heatsinks to be careful of here, just vents on the top and sides for passive cooling. It also allows the amplifier to be lightweight (12kg) and energy efficient, having an idle power consumption – confirmed by Editor PM – of 29W.

The steel casing (available in black or silver) is reasonably pretty, but some might want a little more overt style from their system powerhouse – there's nothing to blemish the front fascia beyond a button with company logo. When pressed, this flashes blue as the amp's tube stage gets into gear and stays a solid blue until pressed again to put the M1200 into 'Output Disable Mode' – preserving the lifetime of the triode when the amp is in standby. This logo also flashes blue if the amp's protection circuit is tripped.

The rear panel is uncluttered. On the left are an IEC socket and power switch, while on the right is a screw-in panel granting access to the M1200's tube. Between are two sets of speaker binding posts, enabling bi-wiring, plus a ground terminal and balanced XLR and single-ended RCA line inputs. There are also 12V trigger sockets for system integration.