Curious if anyone has heard any of the Pass Labs Aleph amps? Thinking of picking up an Aleph 3 for my 2 channel as a solid state compliment to my quicksilver mid monos
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Interesting review as it scores near the bottom of all hp amps heās measured. Iāve never owned nor heard the HPA-1 previously but it has a noteworthy status. I guess we have a long way to go in being able to reconcile measurements to subjectively good sounding gear. The ASR community is toxic so I avoid reading the thread but still an interesting āreviewā.
remove spaces:
https:/ www.audiosciencereview. com/forum/ index.php?threads/pass-labs-hpa-1-headphone-amp-review.39286/
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Well, I picked up a Pass Labs Aleph 3 and have been listening nonstop for the past 24 hours. 30 Watts of Class A, pure single ended amp that doesnāt utilize a āpullā stage like previous Aleph amplifiers.
Itās been a great juxtaposition to my tube amps I use in my system so far. Very airy and instrument separation is magnificent, especially when picking up room acoustics. Listening to āJazz at the Pawnshopā was a treat.
It stands out physically on my shelf with a industrial look. It also runs extremely HOT, so much so that I canāt keep my hand on it for more than 2-3 seconds without being uncomfortable. I guess I am destined to have amps that cannot by touched (looking at you tubes!)
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I would not call that a review, much more of an attempt to takedown, his comments such as needing to max the volume to drive the HD650 is flat out misleading, unless of course his hearing is that bad.
I admit using the HPA-1 with 300 ohm headphones is not my favorite pairing, much better with lower ohm and modern sensitive planar headphones.
Other gripes he had such as no balanced input, well the design is single ended so not everything needs to balanced. There was no mention of the amp topology either, and his rabid followers were going along with the assumptions he preaches on about. Reading through, which I rarely do was eye opening and sad.
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He has stated previously that his normal listening volume is between 95-100dB. I donāt think given that information anyone should question his hearing. Itās shot.
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Heād be way over that at full volume on HD650ās.
Iām not going to get into Amir/ASR bashing, I refuse to visit the site, wish it didnāt exist, think itās harmful to the industry generally, but it is what it is. Just ignore it and move on.
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Not much out there about the amp, and Iām thinking itās not even in production any longer given the Ali Express clones? Definitely provide more detail on it as you get to know it more intimately.
Correct, definitely a vintage amp. My guess is that Nelson Pass transitioned to using the First Watt company for the lower watt amplifier designs since the Aleph J is listed there and it is the child of the Aleph 3 and 30 before it. It would be cool to learn more about the history, perhaps Iāll dig into some interviews he gave
Iāll provide some impressions once I spend more time with it. Good thing it is winter cause its about to heat my entire apartment lol
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I agree it is sad and I stay away from the comments. Regardless if what he does qualifies as a āreviewā or just simply a pure measurement sweep the data is interesting. Almost every objective data point he measure was ābadā from THD, StN, Bandwidth, and distortion to power curves. I usually take these data points with a grain of salt as typically as long as product are within a reasonable range that is really all you can get from measurements. But here his data points are quite bad yet this amp is held in such high regard. Goes to show either we have the wrong measurements or there is some other problem or measurements are truly useless.
But they arenāt, youāve just been convinced that ridiculous numbers matter, I think SBAF covered this recently.
Anything over about 70dB SINAD or any of the other numbers is basically inaudible, itās just a pissing match, almost everything he tests is fine, sorting the results by SINAD as some sort of ranking is pointless.
His assumption that somehow manufacturers arenāt measuring is just plain wrong. The First Watt web site has a bunch of Nelson Pass white papers on his designs (he didnāt design the HP-1 but thatās not really relevant), they are a fascinating read, because they often include measurements, and how he interprets them which is a lot more subtle than my number is bigger than your number.
His papers were the first I saw discuss the importance of the phase of the first harmonic to the sound of an amp.
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If measurements worked on audio nobody here would spend a dollar on cables or DACS to say nothing of streamers and power supplies. We could basically then say the same about every speaker and crossover component, sound quality and characteristics would be a moot point and my phone and a bluetooth speaker are all I need to enjoy maximum sound and satisfy my desires 
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Yeah, Iām in the same boat, I didnāt read the article.
Iām currently working on dialing in this Allnic chain, but Iād really like to hear a Pass HPA-1 some day.
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Here is an alternative measurements made by John Atkinson and Bob Katz from Stereophile a few years ago when the amp was released. Goes to show there is more ways to parse the data and can be used for good or bad intentions:
I have no horse in this race other than owning the amp, and donāt care what others think of it as itās my money, my choices. I will call BS when I see it, and their (ASR) measurements and commentary are BS.
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Pass Labs HPA1
Initial impressions (4 days)
I have been busy so I could only use it for 4 days since it arrived, and not all day but I did my best to focus and analyze the sound of the amp, and also did some relaxed ājust enjoy the musicā listenings.
TLDR: I dont really have anything else of the same price bracket to compare right now but the Pass Labs absolutely kills all of my 1k to 2k amps in technicalities, the detail and resolution have been specially superior. Id say right now the bass is the highlight of its sound (while not overdone). And like every amp some synergies are way better than others.
āmethodā
I have been listening for many hours. For the analytical listening sessions I picked 9 headphones and gave 5 songs to 6 of them and 10 songs to the 3 ones that I liked the most.
60 full songs in total, with a wide variety of music genres, mostly well recorded.
I intentionally picked the few headphones I have that I thought could give the Pass Labs a harder time.
I took a good pause/sleep between each change of headphones to reset my listening. I also heard random songs before the test songs to āwarm upā my ears.
āSourceā
Foobar2000 > Matrix xspdif 3 > Exogal Comet + > Pass Labs hpa1 > headphones
Im using el cheapo chifi and stock cables, sadly none of the great cables that dont break the bank that I ordered in bulk have arrived.
āMy audio preferencesā
just look at the headphones I used. Its varied but they are all brighter leaning, apart from that I love variety the most, and colorful tunings but I dont mind a great neutral tuning at all.
These headphones are some of my keepers so I know their sound perfectly well.
āLets startā
Akg k812
These headphones are very picky.
They sound great with the pass, classic akg vocals and sound is here, amazing piano and string instruments. Better texture and body, more extension on both sides compared to my other amps.
I believe this is the most ātrueā to their signature sound that ive heard from these headphones with all of the amps I tested it with. It just sounds more āAKGā.
My nitpick is I was expecting a bigger soundstage from these but its still rather big.
The k812 in comparison, paired with the yamamoto ha02 has a more coherent stage, more tridimensional sound and better instrument separation.
It also gives them a livelier color but less neutrality and tonal density.
Currently I feel this matchup with the pass labs is trading blows with the yamamoto ha02. Also im very used to the yamamoto pairing so my preference may change. This one needs more testing.
Audeze LCD3pf
This is an amazing pairing, the LCD3pf has become a resolution beast whereas before it was more āfunā oriented. Now its sound is a bit more towards neutral and a lot more technical.
Crazy instrument separation, large staging for an audeze, the texture is so tangible, more extension on both sides, more detailed in general.
The bass had the most amazing change, it rumbles more, its cleaner and meaner, the punch is tighter, again I find it more detailed specially down low.
Also combine the crazy amount of texture in the midrange and treble with its amazing dynamics (both macro and micro) and you get a very physical sound that still has the technical advantages of planars.
Top 3 pairing.
Nitpick @m0n @anyone I would like a bit more sparkle/presence in the treble.
Do you think lavricables or silver dragon could help me get the extra spark I want?
Audio technica ad2000x - yaxi pads
Mmmm, what the hell happened here?
I thought I plugged in an ad2000x yet they sound like completely different headphones. Id say this is the most ive heard headphones change with an amp.
Of course we got more clarity, the details are easier to hear specially the microdetails. Improved dynamics, texture, quite a bit more bass prescense and body which changed the usual frequency response, a lot more extension on both sides, in general theres a big overall SQ improvement.
But what really changed the most was the presentation, the staging and imaging. With other amps I would get a very nice large horizontal focused presentation plus intimate vocals. It was very unique.
With the pass labs its a completely spherical bubble around me, not that big but very dynamic similar to focals actually, but ive had these cans for so long now that its weird hearing them with this new presentation.
My favorite pairing was with the soloist 3xp, but I sold the soloist.
I do miss that matchup because it was really, really good; way more relaxed while still quite technical. It was a very easy listen with the large horizontal presentation, everything was arranged in such a simple way.
Now with the Pass Labs its very extended, sharper edges, very detailed, airy and tridimensional, but with different execution.
However I do consider this a big boi upgrade so ill just have to get used to the new presentation and accept the soloistās signature is gone for good lol.
Audio technica adx5000
These are the headphones I got this amp for, my favorite headphones.
Finally I could properly scale them to see what they are really about. Plus my main problem was the bass volume was not enough because the treble had a bit too much juice.
This has been completely fixed, the treble is less but better sounding, plus a bit of every technical improvement I can think of. I cant express how much im enjoying these.
This is really cool to hear its the best treble ive ever heard.
Top 3 pairing.
Audio technica wp900
I picked these to test because they are currently my bassiest headphones.
I got bassed. And midded. And trebled.
No one has ever properly measured these headphones, when I asked on head-fi I got 2 horrible unknown settings mini dsp charts. Head-fiās Jude was like I got the you bro I got the GRAS ill do it but I think he forgot.
I mention the FR chart because the FR is kind of a mess, I love and describe as a very heavy heavy V shape but also fits in the W shape category.
Theres a massive dip around 300hz that extends all the way up to around 1k. Then there a huge bumps around 3k? Or 5k? Im not sure.
Anyway they improved massively, its like somehow magically created the missing mids specially the lower ones.
So now its more close to the V than to the W shape.
Bassycally they fixed the biggest flaw of the headphones while increasing technical performance in general.
Honorable mention 
Audio technica AWAS
Just wow. Probably the best closed back ive ever heard thanks to the Pass. Also probably the best closed back timbre.
AWAS are usually underrated below their AWKT brother but damn do they both kill it with the pass labs. The synergy they have is really something else.
The vocals man, I can easily understand every word from the vocalists. Amazing for both male and female vocals, and/or lead instruments.
Pitch black background, very great and separated choruses, detailed and clear, great body and tonal density with a balanced tuning that works for almost every song/genre. The tuning ends up being just a very slight v shape.
Top 3 pairing.
Beyerdynamic T1.2 - ATH-ad2000 pads
Excellent timbre in the vocals and lead instruments. Im hearing vocal inflections I had never heard before.
Im noticing some microdetails that I had never heard before as well, the 600ohm beyers really never do stop scaling.
The pad problem: I use ath2000 pads to make the sound more forward and bassy. This is very useful for my other amps, not so much for the Pass.
Bad and not great recordings sound too boomy. These beyers sound boomy in general and way too forward with this specific amp+pads and I dont like that, but im 90% sure that the stock pads/zmf beyer pads will solve these problems.
Im sorry, I didnt have the time to test with other pads, so thats the evaluation here, it has a lot of strenghts but the bass problem is too much.
Grado sr325i gold - shipibo pads
Sound quality was noticeably improved in basically every regard, which is amazing. Both male and female vocals sound improved in general; lyrics are easier to understand.
I will sum it all up in just noticeably better technicalities and presentation.
My favorite thing were the kick drums, they definitely sound like real kick drums.
I wouldnt mind a bit more focus on the treble end like the ath-bha100 amp does but thats a brighter amp.
Anyway these grado are going to be used (almost) exclusively on the pass labs because they sound way too good here.
Honorable mention.
Nitpick @m0n @anyone I would like a bit more sparkle/presence in the treble.
Do you think lavricables or silver dragon could help me get the extra spark I want?
Hifiman HE6seV2 - zmf ori suede pads
Volume needs to be maxed out on both the pass labs and the exogal for a āconcert volumeā which is just good enough headroom I guess.
It has the symptoms of an underpowered headphone, similar to when I used them with a burson funk or jotunheim 2.
I really like the more forward sound that I have here for the lead instrument. But I find the other instruments to be too crowded. Soundstage is similar to an hd650 in a budget solid state. Not the best.
The lead instrument/vocals and the timbre sound real great.
Also the detail/separation/control from memory is not as good as in the burson soloist 3xp by a bit, but pass labsā tuning is a lot better, more natural and with better bass.
Im not convinced at all by this pairing, not because its bad but because I could easily pick and listen a better headphone combo.
āconclusionā
The Pass Labs hpa1 rock hard af.
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Congrats! Iām jealous, the HPA1 is one of my favorite amps Iāve tried in my chain. I had it on loan at the same time I had a ZMF Caldera on loan and the combination was beautiful. Iāve heard this amp excels with planars, which may be why I liked the Caldera so much and you like the LCD3pf so much with it.
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Funny story, this is the amp you used
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With every grado I try the drums sound just like the real thing, like a real battery kit in front of me is being played, so real I cant tell.
On more detailed headphones they still sound natural but you can tell it was recorded and mastered on a studio.
This is new to me (as in having the amp at home) but still I dont think anything for the price that exists will drive grado and audio technica headphones better than the Pass.
Ive got a lot of cans from those 2 brands and they all go hand in hand, very impressive stuff.
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I am soooo happy you are enjoying it! 
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Wow, has any Pass gear been available in black before? Thatās way cool. I love that HPA in black!
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