Pre/Power Amplifiers

Bottom of the five-model XA.5 series of mono power amplifiers, all of them true Class A designs, the XA60.5 offers a rated output of 60W and, it’s claimed, much higher current capability than previous XA models: to the tune of a fi ve-fold improvement. So tough loudspeaker loads, of which there are still many, are grist to the XA.5 series’ mill.
   The traditional virtues of Class A promise compensation in the form of effortless detail and natural warmth of sound. You pay for this in your electricity bills. The XA60.5 is specified as drawing 225W from the wall socket but our mains monitor said 136W for one of the review pair and 150W for the other, for a mains voltage of 240Vrms. On this basis the XA60.5 won’t remain in Class A up to voltage clipping into low impedances.
   As far as aesthetics go, the XA60.5 is straight from the US muscle amp style book: chunky aluminium fascia, large heatsinks along either side and grab handles at the back to make lifting its 27.6kg a little easier. The amp has two pairs of output sockets to facilitate bi-wiring – but they are disposed to either side of the back panel, as if this were a stereo amplifier. Note – as the owner’s manual warns – that the output is balanced, so the black terminal is not connected to earth. A separate earth terminal is provided if you need to hook up a powered subwoofer via its high-level inputs.
   Nobody is going to buy this amplifier for its styling. They’ll buy it for its sound, and that is something out of the ordinary.

SUBTLE SOUND
This is an amp which melds transparency and tonal warmth, subtle insight and dynamic weight with a facility that may well be unprecedented. Its sound is endlessly inviting but you never have the sense that it’s pulling the wool over your eyes, that it is playing some euphonic trick of tonal balance or distortion. Actually it is resolutely neutral, and able to pick up, dust off and start all over again tracks you thought you knew intimately. But it delivers that insight without ever sounding aggressive or sterile. In fact, the XA60.5 lives and breathes as few other amps manage.
   The simple things in audio are sometimes the hardest, a good example being convincing reproduction of a single human voice. Playing Sara K’s interpretation of Don McLean’s ‘Vincent’ [Chesky JD 133] we were struck by the rare persuasiveness of the vocal: its natural warmth, its subtlety of infl ection, its flow. Sara K’s understated, world-weary performance never sounded a more valid alternative to McLean’s towering original than it did via the Pass Labs XA60.5.
   Time for something more complex, so on went Eric Clapton’s ‘Double Trouble’ [Polydor 531 827- 2]. Even before the song started we were thinking we’d never heard the audience conveyed so palpably before, and as we continued listening we realised we were hearing the track anew – that what, for example, had previously been just an on-beat cymbal was now an on-beat cymbal with a distinct character. Having listened to this track a hundred times before, it now seemed newly minted!

VERDICT
Could anyone fail to be enthralled by the sound of the XA60.5? It’s possible if you’ve become used to the glare of a lesser solid-state amplifier or the alluring sophistry of some valve amps. But if you haven’t forgotten what music really sounds like, and you have source components and speakers able to do justice to the amp’s capabilities, then hearing one could well be a life-changing experience.

Originally published in the Yearbook 2010