[FourT6and2]

I suppose if it takes 2-3 hours a day for 30 days to burn it in you could just leave it on for 4-6 hours for 15 days haha. I do believe there is some validity to a higher quality power supply that leads to any discernible sound quality differences between the 789 and HPA4. Had they been identical I think it would be impossible to tell the difference between the two..

Maybe. Power supply effects usually come down to filtering and the amp having enough clean power without any ripple current to meet any output demands. I think in these types of amps they can both handle your average 120v mains just fine, even with dirty power. I do have some professional Furman units I can plug both into but I don't anticipate any difference. I have the Furman P-1800 AR and P-1800 PFR. One is a voltage regulator that outputs a constant, clean 120v source and the other is a power filter that filters out and cleans any "dirty" power to eliminate ripple. I use them with vacuum tube guitar amps because fluctuations in mains voltage greatly affects that sort of thing. But with a digital audio system like a DAC and a solid state headphone amp, I don't think it will do much. But hey, worth a try.

 

[lithiumnk]

I believe the entire chain matters a lot.
Both HPA4 & 789 are dead neutral.
But after trying HE6, Susvara,vintage hps with both amps its an one sided competition. The DACs were yggy, hqaudio dac, HFN r2r2kred & black, dangerous convert 2.

With 789 the above mentioned hps sound thin, lacked dynamics, clipped many times.

Drove both he6 & susvara simultaneously from hpa4. The driver control, slam, dynamics were amazing. Sound was full bodied.

Even with easy to drive cans like adx5000, auteurs, utopia, hd650,hd600 hpa4 was more bodied, dynamic, extracted more micro detail, background was more quieter.

The differences were more noticeable as we upgraded the source.

Also, hpa4 is a serious preamp. This feature is completely ignored by headphone enthusiast.
The 2 ch guys rave about the volume control

YMMV

 

[stemiki]

I think that John Siau wants to say that the measurements are identical both in the new and in the future. But after listening, the differences are heard after a month, in particular the low frequencies become much more focused.
I think the HPA4 is really a definitive amplifier. It is however normal that in the future we want to try something new, even just for the sake of change. With HPA4 you can really feel the slightest difference in changing the source, the cables or anything else.

 

[phthora]

I think that John Siau wants to say that the measurements are identical both in the new and in the future. But after listening, the differences are heard after a month, in particular the low frequencies become much more focused.
I think the HPA4 is really a definitive amplifier. It is however normal that in the future we want to try something new, even just for the sake of change. With HPA4 you can really feel the slightest difference in changing the source, the cables or anything else.

I have about 150 hours on my HPA4 and I haven't heard any difference between it now and out of the box. Since the manufacturer has stated that there is no burn-in effect on the gear and has issued an explicit warning about the importance of brain burn-in, I'm going to go with that as the explanation for perceived differences. Not to broach a controversial topic here or anything.

Normally, I would agree that there is one ironclad reason to burn things in: to expose any manufacturer defects before the warranty expires. Given that the warranty is for five years, that reason doesn't really apply here either.

 

[YooperAudio]

I have about 150 hours on my HPA4 and I haven't heard any difference between it now and out of the box. Since the manufacturer has stated that there is no burn-in effect on the gear and has issued an explicit warning about the importance of brain burn-in, I'm going to go with that as the explanation for perceived differences. Not to broach a controversial topic here or anything.

Normally, I would agree that there is one ironclad reason to burn things in: to expose any manufacturer defects before the warranty expires. Given that the warranty is for five years, that reason doesn't really apply here either.

I've probably got 600 hours on my HPA4, and my experience has been the same.

 

[seb7]

In case any one is interested, here my my Benchmark HPA4 review:

https://www.headphone.guru/the-benchmark-hpa4-headphone-amplifier-the-leader-in-transparency/

In short, I loved it so much that I purchased the review unit.

Nice review! I was hoping you would compare it to the GS-X mini. Is one superior than the other or more or less the same? Which do you enjoy listening to more?

 

[MacedonianHero]

Nice review! I was hoping you would compare it to the GS-X mini. Is one superior than the other or more or less the same? Which do you enjoy listening to more?

Thanks man! Tonally I would say the HPA4 is more on the neutral side of things with slightly better detail retrieval and the GS-X mini is a bit more analog sounding with plenty of punch. Both are superb and it depends on what you prefer (or mood). I think it is very much worth owning both!

 

[Chidi]

Does anybody know how the HPA4 compares to the Niimbus US4+?

 

[AlanYWM]

I was able to audition the HPA4 against the Nimbus US 4+ recently and felt that the Nimbus is the more powerful headphone amp with a slightly warmer sound signature. The headphones used were the Abyss 1266 TC and Hifiman Susvara. Both amp are good sounding and should satisfy most listeners. I just felt the Nimbus sounded fuller with slightly wider soundstage. The Nimbus US 4+ is more expensive of the two. The con with the Nimbus is its volume knob. There is a slight "scratchy" sound when adjusting volume up or down. This does not happen with the HPA4.

 

[FourT6and2]

I was able to audition the HPA4 against the Nimbus US 4+ recently and felt that the Nimbus is the more powerful headphone amp with a slightly warmer sound signature. The headphones used were the Abyss 1266 TC and Hifiman Susvara. Both amp are good sounding and should satisfy most listeners. I just felt the Nimbus sounded fuller with slightly wider soundstage. The Nimbus US 4+ is more expensive of the two. The con with the Nimbus is its volume knob. There is a slight "scratchy" sound when adjusting volume up or down. This does not happen with the HPA4.

Scratchy pot usually means there's DC on it. No bueno.

 

[Chidi]

I was able to audition the HPA4 against the Nimbus US 4+ recently and felt that the Nimbus is the more powerful headphone amp with a slightly warmer sound signature. The headphones used were the Abyss 1266 TC and Hifiman Susvara. Both amp are good sounding and should satisfy most listeners. I just felt the Nimbus sounded fuller with slightly wider soundstage. The Nimbus US 4+ is more expensive of the two. The con with the Nimbus is its volume knob. There is a slight "scratchy" sound when adjusting volume up or down. This does not happen with the HPA4.

Guess I’ll save up for the Niimbus. I auditioned it a few days ago and it’s the best amp I’ve ever heard by a considerable margin. I was hoping the HPA4 was better or at least on par with it, so I wouldn’t have to spend that much. Thanks a lot!

 

[FourT6and2]

An additional $2,000 for a "slightly" warmer sound? No thanks. You can get the same thing with a longer cable, a cable with higher capacitance, or a simple and free EQ tweak.

 

[Arniesb]

An additional $2,000 for a "slightly" warmer sound? No thanks. You can get the same thing with a longer cable, a cable with higher capacitance, or a simple and free EQ tweak.

Warmer sound very well could be because of more quiet power supply. You cant get same result with any eq or anything else. Class a and and One of the best power supply ever is a pinnacle.

 

[twoloszyn]

I’ve never had an opportunity to try out any Violetric or Lake People amps but the Nimbus looks pretty nice. The specs aren’t quite there in comparison to the HPA4 but I’m sure it’s fantastic nonetheless. I tend to agree with @FourT6and2 i don’t think an additional $2k is worth any additional warmth or soundstage. For me, most of my headphones run on the warm side so I prefer power and neutrality. That’s why I ended up getting the HPA4 over the GS-X mini. TETO

 

[JP281]

Does anyone share the opinion some have on the HPA4 being dry/thin sounding? I've talked to some in the hobby and they are put off by this. I've seen posts about owners noticing changes in sound after continuous hours of use, but I can't say that I've had the same experience. Not sounding dry or lifeless either to me.