Like GoVibe’s awesome Portatube, the HP-V1 scores about as good as a hybrid valve headphone amp can. Every hardware test I subjected it to failed to bring it to its knees. It upholds extreme resolution to just about every earphone/headphone on the market; which, I should remind you, isn’t true across the board. No matter how awesome it sounds with Beyerdynamic’s DT880 or T1, the ALO Audio Continental, for instance, isn’t capable of keeping a stable signal when driving low-Ω earphones.
But before I get into the nitty gritty, I’d like to cover background noise and channel balance. I wish I could say that both were perfect. Because the volume pot is extremely sensitive to movement earphone users will run into high output levels even at early low gain volume settings. While driven well, sensitive earphones get too loud, too quick. Sensitive headphones have about double the headroom before they get too loud. Why this is unfortunate is that HP-V1’s power plant is super capable. It can drive anything with absolute stability. But as reality pans out, portable headphones and earphones have very little headroom between great balance and volume levels too loud – or safe – for listening. The Portatube, by contrast, suffers no such problems.
As a consequence, I don’t recommend using the HP-V1 with your favourite earphones or sensitive portable headphones. You very likely will hurt your hearing.
Background noise sits almost on a level with a 2005 iPod nano. Unlike the iPod, however, that noise is clean, untextured, and draws very little noise to itself. It is barely audible through sensitive portable headphones, and whilst music rolls through its circuits, is almost inaudible through any output device.
Naturally, the HP-V1’s sweet spot is high-Ω headphones. In fact, with my favourite DT880/600, control over the usable volume range extends to over 90%, with no marks lost for upticks in distortion. Both balance and pot travel are perfect. Personally, I listen to modern recordings at levels of up to 65% in L gain mode and older recordings at up to 85% before feeling uncomfortable. Neither noise nor undue distortion are exacerbated by raising the volume. But for best performance, keep the volume pot set below 90%.
HP-V1 delivers impressive dynamic range and noise performance that rivals, or beats the Portatube, and which is almost able to match the excellent Portaphile Micro OPA627. The differences are so slight, however; no one will be able to suss them.
Where differences make their entrance is in IMD and THD, both of which are literally orders of magnitudes higher than the Portaphile. But, that’s part of what makes valves fun. I’ve yet to test a valve amp that isn’t massively tipped toward harmonic distortion. And truth be told, distortion done well sounds great. It can be an excellent masking system for headphones that trend to tizzy and wild upper mid heights, or which favour sibilant percussion. Essentially, the HP-V1 adds a softening filter or glow to edges that otherwise, would be harsh.
The good news is that none of that softening affects frequency balance. Balance is perfect at all times. Stereo effects are extremely wide, and can, at times, be overwhelming. In fact, channel separation is so extreme for a valve amp that it rivals high-performance solid state amps. The Portatube doesn’t even come close. Even under load, stereo width can get so wide that the ears, which are used to hearing both left and right channels simultaneously, can get confused. With amps getting higher and higher in performance, the need for crossfeed circuits becomes more apparent. Besides fitting with ample room on the HP-V1, a crossfeed circuit would suit the massive performance the HP-V1 amp serves up.
Update: I should mention that I was able to get a minimum of 9 hours playback time while burning this poor amp in all day IEM comparisons.
Being a fan of the DT880, my options in the valve amp world are many, and great. It is a headphone built for valves. It has some tizz in the upper midrange, and a slight penchant for sibilance in the lower treble. A good valve amp like the HP-V1 smooths that mess out. I’m also an intense fan of the Audeze LCD-X, but one that cannot afford it. The distance between the DT880 and the LCD-X shrinks measurably with the introduction of the HP-V1, which smooths out the DT880’s notches.
Like the Portatube, the HP-V1 projects energy and verve with one hand, and with the other, intimacy. It’s not an intimacy you get from solid state amps. From top to bottom, the output signal is linear, but the feeling you get from the HP-V1 is very different. Unlike solid state amps, the transitions between upper mids and highs is ethereal, almost billowy: audibly delineated, but trending toward liquefaction rather than a ratcheting and de-ratcheting of one frequency into and out of another with absolute precision.
Absolute detail freaks will probably prefer something like the Cypher Labs Theorem 720, or the Portaphile Micro. But even paired with so-called ‘veiled’ or ‘slow’ headphones, the HP-V1 punches enough speed buttons to keep pace with any music. Personally, I prefer mating it to headphones like the DT880 and benefiting from one of the most lush midrange presentations out there. If your headphones have a trippy part, HP-V1 will lovingly melt it away.
Like the Portatube, it’s the maturity of its approach to music that I really like about the HP-V1. Music isn’t something to merely reproduce; it’s something to exult. And exult this amp does. Even tizzy 1980’s New Order and Duran Duran stuff mellows out. Raw ends grow up. And through the HP-V1 my sometimes-shrieky DT880 really latches onto a bit of that excellent Audeze ethos. It is smoother, more intimate, closer. Tizz has left the building. The same goes with the detail-oriented Sleek Audio CT7.
With the exception of the jumpy volume pot, and, in light of excellent HiFi ergonomics, the sole 3,5mm headphone output, there are few detractors to the HP-V1. It is a solid design with solid performance. Provided the right headphone pairing, or a keen liking for softer, more intimate sound, it is an amp that will take your headphones for a ride.
It has plenty of power to boot, too. But lacking perfect control over the volume pot, that power is a detriment
I’ve since cut my hair. I look weeks younger. But the HP-V1 is gone. It’s not like I’ll try endlessly to replace it. I get over things. But I can’t help looking back. The HP-V1 does most of what the Portatube can, but does it in a well-built, well-designed package, both things the Portatube eschew for a garden-variety slop. The main hitch is the volume pot. Where’s the 6,3mm jack? And why the hell does the pot rotate so damn easily and why is it so sensitive? I’m tempted to say, so what? Everything else that makes an amp great the HP-V1 sports in spades. It is one of the finest portable creations, ever. And whether in mourning its passing from my life I drink myself to death or not, that won’t change. I will miss you.
Thank you Fostex; bliss, even when short-lived, is after all, bliss.