Preamplitude. By replacing our Esoteric C-03 transistor preamp, the HPA-1 low-balled its €10'000 when-new sticker by a whopping 60%. With such a hair cut, it also dropped to the floor thus ready for the waste bin 2 x RCA and/or 1 x XLR outputs; balanced inputs; 3-tier variable gain of 0/12/24dB; remote control; input naming and gain trim; and a full-size chassis. But my intro already covered all that. The Pass is more minimalist. Being reminded by way of an A/B and how more coin will buy more features merely kept it real. Of sorts. On sonics, things got rather more unreal. That's because for our rig's virtual pipes, the HPA-1 acted as potent Drano®.

I previously exploited Buckminster Fuller's tensegrity word in a Keep-It-Honest feature for Berlin contributor John Darko's DigitalAudioReview.net site. Pay it a quick visit. It's a brief riff but covers ground to explain the audible result of superior drive. In automotive terms, from perhaps a turbo-boosted big engine without lag, we instinctively understand what it means. You step on the gas, the vehicle lunges forward. How forcefully it does; how well it maintains control and grip on the asphalt; how effectively it transfers power to the wheels whilst towing a trailer or scaling an endless ascent at freeway speeds... all of it is about how drive and torque intersect into actual hardware behaviour; and how that shapes the user experience.

Musically, higher 'torque' or 'drive' don't accelerate tunes. The same track doesn't suddenly finish a few seconds sooner. It doesn't go any faster. Yet subjectively, it can still feel that the same passage of time was passed more vigorously, more energetically... more driven. That's in contrast to leisurely meandering for which hifi terminology has the pipe'n'slippers visual. The real reason why music can appear to move through time in more active or passive fashion has mostly to do with the snap and spunk of dynamic pulses. In terms of beats, those literally keep time. If a tune plays in the pocket to groove and hang tight, it tends to elicit a bodily response. It's the archetypal British pace, rhythm & timing thang. Those ingredients result in tapping feet, bopping heads, swaying hips; the lot. All of it falls back on superior drive. A secondary aspect is authority particularly in the power zone of the upper bass and below. If we visualize our hifi as a delivery system which ends in a more or less pressurized jet of water, that jet is either fit to clean gunk off a car without much elbow grease; or only makes it wet whilst we have to do real scrubbing. Similarly, better musical drive seems to result in higher acoustic pressurization. And that's where and how the HPA-1 had the C-03 in its rear-view mirror. As a car, it was smaller but had the beefier torquier engine. It made for a sportier more exhilarating drive.

Likely due to very good resolution, not only didn't any of it affect the system's lucidity. Rather, it upped that quality too. I'm doubtful that it was an actual resolution increase. The higher musical tension, dynamic striations and punch simply impacted my perception of low-level stuff as well. What wasn't in question was the hilarious Harry Potter line of "it's gonna be a bumpy ride" by the Rastafarian shrunken head in the bus; and how it pointed directly at the bumpier bass textures I now had with the HPA-1 driving the FirstWatt SIT-1 monos. Call it bass bounce, call it more pep in the step, call it more tightly coupled informativeness of the musical road conditions. The end result was greater musical vitality. Of course that's not a proper hifi term. For that, we reach out for the old standby of bass authority and tautness which get pulled out whenever one discusses proper muscle amps. Perhaps the most communicative takeaway line to really profile the Pass Labs HPA-1 is to call it a muscle preamp?

Checking with the higher upstairs authorities, I think that's a keeper. It suggests all the right things without having to spell them out. It also suggests an alternate spelling for HPA-1: Hot Pre Amplifier. Should one really expect that it would behave any different into headphones where the spelling becomes Head Phone Amplifier? With the frontal mode switch, a headphone can remain permanently jacked in. Just press 'preamp' to defeat the 6.3mm output. It makes for very easy conversion.