My HPA-1 Review:
Introduction.
With the marketplace for stereo and headphone gear as crowded and opaque as it has ever been, my philosophy has been to try and identify respected designers and companies whose philosophies and design values match my own.
Though I’m not much of a DIY-er (beyond putting together amp-kits and re-terminating cables), my more DIY-savvy friends always rant and rave about Nelson Pass and his contributions to DIY audio. Mr. Pass’s designs are ubiquitous, and his candor, honesty, and intelligence are apparent to anyone who has read the white papers on the Pass DIY site. The Pass DIY white papers are so full of useful tidbits and insights that having read them you quickly come to respect respect Mr. Pass and his experience in the two channel audio world. Living in the Bay Area, I’ve met Mr. Pass a number of times at the Burning Amp Festival and I’ve always found him welcoming and happy to help and answer questions.
Suffice it to say, I’m a fan of Pass Labs as a company. I own a Pass Labs XP-10 preamp and use it in my two channel setup. When I heard that Pass Labs was introducing the their first dedicated headphone amplifier I had to hear it. Thanks to Todd I was able to spend a week with the HPA-1 and got to use it in both my office and home rigs.
Is a solid state amp the right choice for you?
Before I go in to my impressions of the HPA-1, I want to take a step back and talk about sound signatures and pasta sauce. Why pasta sauce? Malcolm Gladwell gave a TED Talk about 10 years back (https://youtu.be/iIiAAhUeR6Y) where he talked about the perfect pasta sauce. It turns out that after analyzing data from massive taste tests that there is no such thing as a perfect pasta sauce. The pasta sauce taste test data clustered around different varieties. Some people really liked chunky pasta sauce, even though others didn’t. Some people liked their sauce spicy, even though others didn’t. Some like their plain, etc. Rather than there being a single perfect pasta sauce that would please everyone, the key to cracking the pasta sauce market turned out to be to offer all the different sauces different sauce varieties the taste testers clustered around.
I think the market for amplifiers is like the market for pasta sauce. There just isn’t one amp that is going to satisfy everyone. Some people prefer the sound of OTL tube amps, some people like their amps to have transformer coupled output, some people are going to like solid state amps and some wont.
To that end, I think the “solid state sound” isn’t for everyone. I’ve found that friends who listen to their music a lot louder than I do tend to hear solid state amps as “thin” sounding with too much or treble emphasis. I don’t hear solid state amps this way. What I want out of a good solid state amp is a “wire with gain.” I don’t want or expect added lushness or romance or a holographic soundstage. Just give me what is on the recording please!
If you like the sound of solid state amps then you absolutely should try and audition the HPA-1.
My Impressions.
My overall impression is that the HPA-1 is solid state done well. I found the amp to be clear, neutral, and punchy. The HPA-1 is a very enjoyable listen, and I was able to listen for hours without my ears feeling fatigued. When I listened to the HPA-1 I wasn’t left wanting for more.
I used the Sennheiser HD600/650/800 trinity of headphones to evaluate HPA-1. In my experience, the Sennheiser trinity are as adept as any current production headphones at revealing the character of the amps that power them. I thought the HPA-1 was an excellent match for the HD600/650/800 trinity. While I didn’t use any planars or IEMs in my evaluation, the HPA-1 has a low output impedance and high power output so I don’t imagine it’d have any trouble getting the best out of just about any headphone.
During my evaluation I mostly listened to jazz, classical and well recorded classic rock. I used the Schiit Yggdrasil DAC (via USB) and the OPPO BDP-105 (playing SACDs) as sources. The HPA-1 did well with everything I threw at it. Newer, “hotter” recordings with less dynamic range didn’t sound so great, but the only conclusion I draw from that is that the HPA-1 doesn’t “lush up” the music. I think that is a good thing.
I could easily live with the HPA-1 as my only amp.
Comparisons with other amps.
I was able to compare the HPA-1 closely with my Bottlehead Crack-a-two-a and a DIY SuSy Dynalo I had on had.
With regards to the Crack 2, the two amps sound very different. The Crack 2 is more forgiving than the HPA-1 and tonally sits on the “warmer” side of neutral. By “warmer” I mean that the Crack 2 tilts towards the bass and low-mids rather than treble. The Crack 2 also has more quantity of bass, even if it is less controlled than the bass on the HPA-1. The HPA-1 sounds more neutral and clear. The HPA-1’s bass is punchier and better controlled. While the Crack 2 is the more fun, relaxing amp, the HPA-1 feels a lot more accurate and honest to the recording. While I personally would choose the HPA-1 over the Crack 2, I can easily understand fans of OTL tube amps doing the opposite.
I heard much less of a difference between the HPA-1 and the DIY SuSy Dynalo. Both seemed to me to be well designed solid state amps and both predominantly have the “wire with gain” character I look for in solid state. Both sounded clear, neutral and punchy. In fact, the amps sounded close enough that I had a hard time telling them apart. That is a good thing as I liked both the HPA-1 and SuSy Dynalo quite a bit. In a comparison under meet conditions I heard the HPA-1 as being the slightly more powerful amp of the two with better control down low and a slightly bigger soundstage, but the room was noisy and the differences between the two amps could just as easily fall in the margin or error that exists while trying to do comparisons at a headphone meet. Honestly, I’d be happy having either amp in my stable.
Build Quality.
The build quality of the HPA-1 is fantastic, with one notable caveat. I think the TRS jack on the front was a poor choice and looks bad on an otherwise gorgeous amp. With that sole exception, the amp is a stunner in person. The HPA-1 looks and feels like a solid piece of kit and looks much better in person than it does in photos. Like my Pass Labs preamp, the tactile sensation of operating the volume knobs and inputs is absolutely top notch. I thought the HPA-1 looked and fit great as part of a desktop rig.
Cons.
For an amp that costs as much as the HPA-1, it’d be nice if it was fully balanced. At the very least I think the HPA-1 should have had a balanced input option despite only being a single-ended output. I am also not sure why preamp functionality was included on the HPA-1 as I would never consider using it as a preamp without a remote. A remote would have been a nice addition with the HPA-1.
The other big con of the HPA-1 is its price. Value is in the eye of the beholder, but to me I think the amp is a bit too expensive. I’d strongly consider purchasing the HPA-1 for myself if it fell in the $2,000-$2,500 price range. At $3,500, it is a bit tougher for me justify.
Conclusion.
The Pass Labs HPA-1 is a very solid debut from Pass Labs. To my ears it is a well executed solid state amp. The HPA-1 sounds clear, punchy and neutral. It was a very nice pairing with the Sennheiser HD600/650/800 trinity and should be flexible enough to bring the best out of most current production headphones. I could live with the HPA-1 as my only amp, especially if it wasn’t quite so expensive.
Fans of solid state amps should definitely give this one a listen.
