I have seen some spectacular solder residue in Topping products. Maybe washing the PCBs properly washes out the good numbers? 
Depends. When there is a lot of airborne conductive stuff in the factory, that could land and stick on the flux. On in case of corrosive flux, it could eat its way into plastic component packages.
The mind boggles, honestly.
Yeah, to me its a badge of honor when soldering here…that the board is cleaned and its nice and shiny joints…really professional looking etc…
When I prototype its often a mess of sorts, but I stop myself and clean up stuff before it gets really hard to clean up!
This unit was not a Topping…
How would you compare the Pass Lab’s unit to a V281/V220? I can’t remember if you owned one.
Many of the qualities and workmanship you discussed here sounded sonewhat familiar to my V220.
Hi Shane…
This is one amp that has alluded me, close to buying one several times but never connected. So I cant opine between the two…from what I read and understand the Vioelectric stuff is made very well…they are pricey as well as you climb up their ladder.
The V281 is a beautiful looking amp to me…I would think with its power it can drive almost anything out their. The voicing is said to be really clean, clear and clinical…sounds like the HPA-1 might be a tad
warmer of more “musical” ?
Maybe someone will chime in who has one…would love to try one someday.
The 281 is a warmer smoother generally more relaxed and wide amp, similar to the voicing of their older amps. The newer series of violectric like the v550 for example is a cleaner and more accurate approach, fairly neutral, but not reaching into the clinical side of things yet. I’d personally say the pass is a bit more balanced tuning wise than the v281, but the v550 is more linear and “studio” sounding than the pass. DAC wise you already have a really good pairing for the 281 since if you have a warmer more smooth and relaxed dac, the pairing can become a bit too rich or potentially mushy. The soekris tightens and cleans things up a bit and leans the pairing overall neutral with a bit of warmth. The v550 also pairs well but that will definitely lean more neutral dry
I found this at: https://parttimeaudiophile.com/2017/02/05/review-pass-labs-hpa-1-headphone-amplifier/
Part of the review:
Last but not least, my reference amp, the Violectric V281 ($2879 with the upgraded relay-based volume solution). Choosing between these two amps is incredibly difficult for me. I love the V281 for its tasteful warmth, punchy dynamics, and emotive midrange. It does highs in an ever-so-slightly smooth way, taking just enough of an edge off without dulling the presentation. That makes it both more musically engaging and less transparent than the Pass amp — which is something that may or may not be a good thing depending on your priorities.
Listening to Jimi Hendrix Cry of Love versus the re-released versions of those same tracks compiled on First Rays of the New Rising Sun, it’s easy to spot the differences with the Pass amp. There’s improved clarity in Jimi’s vocals, while many poor overdubs are removed to reveal more musical content. The Violectric presents this as a sort of “hmmm, yes I suppose it is better”, while the Pass is more “Wow, that’s a huge difference!”. If subtlety and musical illumination is your thing, the Pass really delivers.
That said, the V281 sometimes gets things right to a larger extent. On Yellowcard’s “How I Go” — which is unrelated to but very clearly inspired by the Tim Burton film Big Fish — the Pass amp plays it more light and ethereal, while the Violectric is meatier and more expressive. The female guest vocalist absolutely steals the show on his song (I later discovered her to be Natalie Maines of Dixie Chicks fame) and it seems the Violectic does a better job of conveying the full emotional weight of her voice. The Pass is already excellent here, and I wouldn’t know I was missing anything unless I heard the two amps back to back.
I could go back and forth citing different examples where each amp has an edge over the other. It comes down to individual tracks and of course headphone pairings. I could happily live with either amp or, better yet, live with both where they compliment one another. Those of you who know how much I love the Violectric V281 will understand how big of a compliment this truly is.
Hope this helps…
Alex
I’d agree with that take, although it is somewhat harder to compare the pass to the v281, since in most respects the pass is a step above when it comes to technical ability (albeit with a different signature), so somewhat different performance tier, but interesting comparison nonetheless
One thing that pops out to me is there are a few amps that have stood the test of time…in that the designer took a long time to get it “right” before releasing or making them…and with little or no upgrade or significant changes…
The Bryston BH1 out since 2012, still the basic same Class A op amp design, with a minor tweak for gain. Still going strong with a 20 yr warranty…$2295.
The HPA-1 the same tank amp since 2016…no real changes at all.
The BH Crack, and BH Mainline have been around for years and years, yes DIY kits but the same basic setup and design…real classics.
These amps or devices IMO become heir-loom devices or items. My HPA-1 will never be sold by me, it will be here as long as I can hear music well…and then it will “pass” along to my son…
I still remember when it retailed for like 1.4k, was really a good deal in the past lol, still worthwhile now even at current price
Just wanted to jump in quickly, the Pass is over-built. I had an issue with mine once and emailed in for help. I got a very prompt response telling me exactly what went wrong and that it was a 2 minute fix. I did exactly as I was told and thus maintained their 100% reliability standard with never one single HPA-1 returned for a repair. The gorillas at UPS did their best to toss my amp around and break it and were unsuccessful, worst they had done was dislodge a single connection. That in itself was a feat of extreme abuse during delivery.
Next reason why the HPA-1 is a worthwhile investment to some of us, it’s a damned good pre-amplifier, worth its asking price alone as a pre-amp. That is value added to those of us who desire that feature.
Lastly is the sound signature, it’s very euphonic for a solid state amp, and takes well to a variety of DAC’s and is forgiving of a low quality front end, thus potentially saving you twice it’s cost, minimum in upgrades on your front end to extract the performance it is capable of.
These intangible differences I have found worthwhile and relevant to the cost of this amplifier and should be noted for individuals interested in purchasing one. These are not opinions, these are facts based on hard experience of my ownership of an HPA-1 made by Pass labs.
Nice find, thanks. I love my V220, which @MON recommended strongly to me. I found it to be shockingly expensive for a stripped down V281, with lower power and no balanced headphone output.
I liked it when I got it and it has grown on me more ever since. The iFi Pro iCAN is a powerful machine with lots of toys, but with certain headphones, I actually prefer the V220. I think I am very lucky to own both and combined with my LP, I have no interest in buying anymore amps.
But it is SO hard to not fixate on a great product, be it an amp or a headphone. 
