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Review and Measurements of Benchmark HPA4 Headphone Amp/Pre

It’s an abomination.
Keith
Keith, Beauties in the eye and all that.
As a retired machinist myself, I've stated a number of times here how much I admire the beauty of the D'Ags case work.
Some of the Pass Labs stuff comes close, but this is the Mona Lisa of Hi Fi, JMHO
If I had Elon's size of wallet, I'd probably have a room full of his components.
Even if they weren't plugged in and I was using some Benchmark gear running hidden behind. LOL
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Perhaps even more hideous in black, they are never going to get to Moma.
Keith
 
The volume control for all inputs (even the DAC) was analogue! it used chip based, digitally controlled, fully balanced resistor ladder array. Four ladders to control the balanced output, which was defeatable.
I think it first came out about 12 years ago! There is a mini review here on ASR. The analogue input had a measured noise floor of less than -140dB, with minor spikes reaching -130dB.
Sounds very similar to the level control arrangement of my old Emotiva DC-1 DAC
Amir measured it here some years back, not great but not horrible either.
It's still in use here, mainly as the computers desktop control center and also for it's excellent headphone amp.
IMHO one of the nicest little products Emo had ever produced, out of production now for many years.

This is from the user manual,
"Dual Muses 72320 digitally controlled analog ladder volume control chips.
The volume for each fully differential channel is controlled by a separate Muses 72320
precision volume control IC, operated in our unique and proprietary dual gain control
mode
(by simultaneously controlling both signal level and the gain of the gain stage itself,
this technique optimizes the signal handling at various gain levels to achieve the
absolute best noise and distortion performance at any given setting)."
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Keith, Beauties in the eye and all that.
As a retired machinist myself, I've stated a number of times here how much I admire the beauty of the D'Ags case work.
Some of the Pass Labs stuff comes close, but this is the Mona Lisa of Hi Fi, JMHO
If I had Elon's size of wallet, I'd probably have a room full of his components.
Even if they weren't plugged in and I was using some Benchmark gear running hidden behind. LOL
View attachment 387968
Yes beauties, but not in this black copper scheme yuck....
Silver copper looks sooo much better ;)
 
It sure costs a hell of a lot less !!!
Benchmark also has a few other competitive pieces in their lineup.
The $2950 LA4 is the pure line preamp sans the dedicated headphone amp of the $3499 HPA4
There's also a couple lower cost options of the DAC3 which can be directly connected to amps but yet include one of the best DAC's available anywhere.
Any would be awesome for a SOTA front end to a pure 2ch system.
Decisions decisions. LOL

I have the benchmark DAC 2L as my DAC.
It was nice because when I wanted to, I could use it as a line stage instead of my tube preamp.

Since I often liked what I heard, I bought the benchmark LA4 preamp, not just on the potential of better performance, but because it had the features I wanted and needed for operating my system.

I’m satisfied owning benchmark gear because I know I’m buying into a company with great engineering chops.

Also, I found the company very helpful when I had various questions in how I was implementing their gear!

Top shelf company!!!
 
I currently have the SMSL SP400 (THX 888 headphone amp) paired with the Lynx Hilo DAC.
The Hilo's XLR output level is set to +24dBu (12.28V) and the SP400 is set on High Gain.
Eventhough the Hilo is old tech (Cirrus Logic CS4398 DACs), due to its +24dBu output, the clarity and dynamics I get in sound with this combo is simply jaw dropping.
Paired with regular 5.2V DACs from Topping, SMSL or whatever, the sound is OK, nice and detailed. But with the Hilo, it's no contest, even the SMSL D400ES with the latest ESS 9039PRO DAC sounds bland by comparison.
Trying lower voltages out of the Hilo resulted in a less dynamic sound so I will never ever buy a DAC again that doesn't have the pro +24dBu output level.
My question:
In my particular case, is there any benefit from buying the Benchmark HPA4 headphone amp?
It's the same THX 888 amp, but half the power at 32 Ohm (SP400 can dissipate 6W into 32 Ohm), and ofcourse...it's 6x the price :)))


The headphones I use are AKG K701, Hifiman Arya Stealth and HE1000se.
Thanks!
 
I currently have the SMSL SP400 (THX 888 headphone amp) paired with the Lynx Hilo DAC.
The Hilo's XLR output level is set to +24dBu (12.28V) and the SP400 is set on High Gain.
Eventhough the Hilo is old tech (Cirrus Logic CS4398 DACs), due to its +24dBu output, the clarity and dynamics I get in sound with this combo is simply jaw dropping.
Paired with regular 5.2V DACs from Topping, SMSL or whatever, the sound is OK, nice and detailed. But with the Hilo, it's no contest, even the SMSL D400ES with the latest ESS 9039PRO DAC sounds bland by comparison.
Trying lower voltages out of the Hilo resulted in a less dynamic sound so I will never ever buy a DAC again that doesn't have the pro +24dBu output level.
My question:
In my particular case, is there any benefit from buying the Benchmark HPA4 headphone amp?
It's the same THX 888 amp, but half the power at 32 Ohm (SP400 can dissipate 6W into 32 Ohm), and ofcourse...it's 6x the price :)))


The headphones I use are AKG K701, Hifiman Arya Stealth and HE1000se.
Thanks!
The HPA4 would optimize the gain staging between your DAC and the internal THX 888 headphone amplifier. The SNR and THD+N of the HPA4/LA4 input stage is nearly constant over a very wide range of input gain settings. This allow the use of a 4 Vrms consumer-grade device or a +24 dBu professional-grade device while extracting the maximum performance that either device can produce.

In contrast, the performance of a headphone amplifier with a traditional gain pot will be very sensitive the the input level of the signal. A high signal level will be required to achieve a high SNR within the headphone amplifier itself.

Sorry the HPA4 is so much more expensive than products made in China. All of those relays and precision resistors add up. We replaced a pot with 64 relays. This is not very cost-effective, but the performance is awesome. We also build our products in the USA.
 
The HPA4 would optimize the gain staging between your DAC and the internal THX 888 headphone amplifier. The SNR and THD+N of the HPA4/LA4 input stage is nearly constant over a very wide range of input gain settings. This allow the use of a 4 Vrms consumer-grade device or a +24 dBu professional-grade device while extracting the maximum performance that either device can produce.

In contrast, the performance of a headphone amplifier with a traditional gain pot will be very sensitive the the input level of the signal. A high signal level will be required to achieve a high SNR within the headphone amplifier itself.

Sorry the HPA4 is so much more expensive than products made in China. All of those relays and precision resistors add up. We replaced a pot with 64 relays. This is not very cost-effective, but the performance is awesome. We also build our products in the USA.
The SP400 has "high precision low noise 256 level relay volume control" (see the link in the previous post).
Isn't this the same as yours?
Anyway, I'm on a hunt for DACs that output +24dBu to test this headphone amplifier. I have never heard something like this before, and I tried Violectric, RME ADI-2 DAC's integrated amp and many others.
I've placed an order about two weeks ago for a Benchmark DAC3 B to test with the SP400.
Can't wait to get here sooner :) !!!
 
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The SP400 has "high precision low noise 256 level relay volume control" (see the link in the previous post).
Isn't this the same as yours?

A more useful link would have been to the review by Amir, where you also get a picture of the inside. Then you would know already that it's world's apart between Benchmark's relais implementation and SMSL's.


That's all there is. Then look here:


Note the upper relais board covers the lower relais and CPU board, so more compoents than visible. State of the art won't be cheap.
 
Hello folks, I am thinking of picking up a Benchmark LA4 and am going through the pdf manual right now.

My apology for the noob questions:

1) I will be connecting "consumer grade" upstream device (dac with consumer grade xlr output) to the LA4. According to the manual, it advices to set the LA4 input BOOST to 10db on that XLR input. I am a bit confuse what it means really?

2) Do the LA4 XLR output and RCA output simultaneously so I can use the XLR output to my power amp and RCA output to my two subwoofers?

3) As per 1, 2) above, I will be connecting a "consumer grade" dac XLR output to the LA4, then XLR output to my power amp and RCA output to my two subwoofers. Does it mean I should still set the LA4 input BOOST to 10db on the XLR input?

4) I plan to use 1 RCA input at "unity gain" for connecting my Anthem MRX1120 receiver for movies and PC games AND 1 XLR input at "unity gain" for connecting my Schiit Freya +. Does it mean I just set 1 RCA input and 1 XLR input at 0db and that would mean they are now at "unity gain" = ht-bypass?

Thank you folks!!! Much appreciated

D
 
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Hello folks, I am thinking of picking up a Benchmark LA4 and am going through the pdf manual right now.

My apology for the noob questions:

1) I will be connecting "consumer grade" upstream device (dac with consumer grade xlr output) to the LA4. According to the manual, it advices to set the LA4 input BOOST to 10db on that XLR input. I am a bit confuse what it means really?

2) Do the LA4 XLR output and RCA output simultaneously so I can use the XLR output to my power amp and RCA output to my two subwoofers?

3) As per 1, 2) above, I will be connecting a "consumer grade" dac XLR output to the LA4, then XLR output to my power amp and RCA output to my two subwoofers. Does it mean I should still set the LA4 input BOOST to 10db on the XLR input?

4) I plan to use 1 RCA input at "unity gain" for connecting my Anthem MRX1120 receiver for movies and PC games AND 1 XLR input at "unity gain" for connecting my Schiit Freya +. Does it mean I just set 1 RCA input and 1 XLR input at 0db and that would mean they are now at "unity gain" = ht-bypass?

Thank you folks!!! Much appreciated

D
I have the HPA4 and love it! There are a ton of options on setup and config. I’m not going to try to answer all your questions. You know who does have all the answers? Benchmark! I’ve pestered them with many similar questions and Dan and Rory were always patient with me and gave me excellent information. Call them in NY. They’ll give you the info you need.!!!
 
I've placed an order about two weeks ago for a Benchmark DAC3 B to test with the SP400.
Can't wait to get here sooner :) !!!
Received the DAC3 B two weeks ago to test with the SP400 and daaaamn...it bests even the Lynx Hilo at +24dBu. It has the same sound signature as in tonality and dynamics but it is cleaner and more transparent.
To be fair I initially thought Benchmark was full of marketing gimmicks because usually the more you talk about your product and overhype it the more you're trying to cover some faults, but after hearing the DAC3 B I will have to take back everything I thought...
I have pretty extensive experience with pro products and this DAC is the most neutral I have ever heard so far. It beats the crap out of everything out there from SMSL, Topping, FiiO or whatever (as it should as it costs atleast 3x the price of their products) although it doesn't use the latest tech (one ES9028 Pro vs offerings with two ES9039 Pro, etc).
No contest.
If the HPA4 is built on the same principles as the DAC3 as in no added coloration or sound "sweetening", softening, etc then I want it badly now.
I've also measured the total distortion of the Hilo+SP400 and DAC3 B+ SP400 combos both at +24dBu via the E1DA Cosmos ADC Grade 0. The Benchmark is better.
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I just got my HPA4 with two AHB2.
I see that even with +10db setting the volume is not the high.
I find that I am at almost 90%.
Previously on my Denon PMA-A110 I could not go much above 40% top 50% (depends on the recording dynamic range and mstering).
My souce in from HoloAudio May DAC KTE.
All connections are XLR.
Any idea?
 
I just got my HPA4 with two AHB2.
I see that even with +10db setting the volume is not the high.
I find that I am at almost 90%.
Previously on my Denon PMA-A110 I could not go much above 40% top 50% (depends on the recording dynamic range and mstering).
My souce in from HoloAudio May DAC KTE.
All connections are XLR.
Any idea?
I don’t use the AHB2 but it should have gain settings low, medium, high.

I used to own the Holo Cyan 2 which xlr voltage output for dsd was only 2.25vrms.

My power amp has gain of 21db.

Benchmark LA4 with input gain at +10db

My regular listening volume on the LA4 would be about -15 to -20db

My ifi pro idsd on the other hand has fixed professional mode xlr output at 11vrms, again would be about -6db with dsd.

Benchmark LA4 with input gain of 0db
My regular listening volume on the LA4 would be about -20.

I have to set digital volume at -7db to allow headroom for audiolense convolution

I guess the bottom line is the AHB2 should work if you set them to mediums/high gain settings.
 
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I have the same setup. I run close to max volume. It ramps up slowly. Then maxes out fast. I’ve never been at full volume. I talked to the guys at Benchmark and they said it was normal behavior. I’m sure there is a better technical answer.

If you’re in doubt, give the folks at Benchmark a call. They are experts and very friendly.
 
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