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Benchmark HPA4 based on THX AAA Amplifier

etc6849

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@amirm
I can if he needs me to send an HPA4 still I can, but I think Benchmark is sending him one?

I mainly use the office setup for headphones, and actually have the speakers posted on craigslist right now. I know there are measurements in the HPA4 manual for line in to line out, and it is discussed here: https://benchmarkmedia.com/blogs/application_notes/benchmarks-256-step-relay-controlled-attenuator

If you were sending him your unit for review, then you deserve a great thumbs up for that!
 
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amirm

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@amirm
I can if he needs me to send an HPA4 still I can, but I think Benchmark is sending him one?
They made an offer a while back but I have not yet asked them to send one in. As noted though, testing an independent unit is always best, even though it will cost both of us a few dollars for shipping.
 

ShiZo

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@etc6849 , with my focal headphones that are sensitive, like my elegia, I can hear the noise when I turn the amp to its absolute max. Is it the same with you?
 

Kyle / MrHeeHo

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@etc6849 , with my focal headphones that are sensitive, like my elegia, I can hear the noise when I turn the amp to its absolute max. Is it the same with you?
The Focals should probably be used on the lowest gain setting. What are you using it at?
 

etc6849

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@amirm
I'm not against it and completely trust you. However, it's the insurance on it that is expensive :( Just sold a lot on ebay, and I'd guess it'd be around $50 each way with insurance.

@ShiZo
Using my Focal Utopia's:
I hear a slight noise at +15dB (max), almost can't hear any hiss at +10dB, and can't hear anything at +7dB. This is with the DAC3 connected.

EDIT: however, you shouldn't have it anywhere near +15dB unless the source you are using doesn't have enough output...
 

etc6849

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I don't doubt Amir will do a fantastic job and cover the return shipping. It's just shipping something that expensive worries me. It probably shouldn't though. I also don't blame him for doing cheaper amps first since that covers a bigger audience.
 

Jerry Sobel

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Has anyone heard or own the LA4? I have been thinking about getting one to put into my Benchmark system.
 

ShiZo

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Does the la4 work with headphones?
 

Sal1950

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laidick

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No, if headphone use is desired get the HPA4

Does the LA4 support AV bypass mode?

Since I would like to have this preamp sit between my AVR and power amp.

Thanks!
 

Kal Rubinson

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Does the LA4 support AV bypass mode?
Not per se. However, you can set a "preset" for any given input which is not responsive to the volume control. That "preset" can be at any value including 0dB gain.
 

BigVU's

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Ok so, I just went through this, having questions about THX and now this amp has THXAAA being thrown around and stamped on this amp? Why? Is it marketing gimmicks or real standards that mean something... clearly this amp has set the standard based on the measurements in this review. And this company didn't just buy the THX logo, they actually partnered with it?
 

Hugo9000

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Ok so, I just went through this, having questions about THX and now this amp has THXAAA being thrown around and stamped on this amp? Why? Is it marketing gimmicks or real standards that mean something... clearly this amp has set the standard based on the measurements in this review. And this company didn't just buy the THX logo, they actually partnered with it?
This is a different matter from the THX certification/labeling of home theater gear discussed in that other thread.

THX AAA ("Achromatic Audio Amplifier") is a particular trademarked technology from THX.
https://www.thx.com/mobile/aaa/

An interview with Laurie Fincham of THX (he was a key figure at KEF for ages, by the way):
https://www.pooraudiophile.com/2015/04/laurie-fincham-achromatic-audio-amplifier.html

Benchmark was the first company to use THX AAA, in their AHB2 Power Amplifier, measured/tested by @amirm here at ASR:
https://www.audiosciencereview.com/...-and-measurements-of-benchmark-ahb2-amp.7628/

Then there is the Massdrop THX AAA 789 headphone amp reviewed and measured by Amir:
https://www.audiosciencereview.com/...easurements-of-massdrop-thx-aaa-789-amp.5001/

And of course, the Benchmark HPA4 in this very thread, which Amir reviewed and measured here:
https://www.audiosciencereview.com/...nts-of-benchmark-hpa4-headphone-amp-pre.8141/


Here is more:
https://www.audiosciencereview.com/...gn-of-benchmark-ahb2-and-thx-technology.7909/
 
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amirm

amirm

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Ok so, I just went through this, having questions about THX and now this amp has THXAAA being thrown around and stamped on this amp? Why? Is it marketing gimmicks or real standards that mean something... clearly this amp has set the standard based on the measurements in this review. And this company didn't just buy the THX logo, they actually partnered with it?
As noted by Hugo, this is the real deal. THX resurrected an old technology (feed forward) and made it fresh again. Then worked with Benchmark to design this amplifier. It is superb technology. So no relation to their logo program on home theater gear.
 

BigVU's

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I went to their site with my card in hand and well - sorry we are making more as quickly as possible - message. WoW! Now I really want one of these things!

THX - I mean again I don't know enough about it or the measurements etc.. but they seem to linger in the air with their logo and since they have some real deal engineers putting in some real deal technology that achieves some real deal measurements I think it gives me enough logic to say this is the real deal as well. :) The noise floors are ridiculous in your tests of the AHB2 and the price could have been 20K and no one would have likely batted an eye considering what they are able to do... no?

Good Stuff! Need to call the hifi shops to see if they have one to listen to.
 

RichB

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Does the LA4 support AV bypass mode?

Since I would like to have this preamp sit between my AVR and power amp.

Thanks!

Not per se. However, you can set a "preset" for any given input which is not responsive to the volume control. That "preset" can be at any value including 0dB gain.

I use the LA4 with one fixed level input for AV bypass and the other for my UPD-205 DAC and it works very well.
However, if you are not using a Benchmark DAC2/DAC3 the remote cannot be used to discretely select an input. I worked with Benchmark support to emulate this by altering several settings so that one XLR is directly selected and the other is selected by selecting the first and then sending a next input command. I have submitted an enhancement request to Benchmark to provide a mode that supports discrete inputs.

- Rich
 

laidick

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I use the LA4 with one fixed level input for AV bypass and the other for my UPD-205 DAC and it works very well.
However, if you are not using a Benchmark DAC2/DAC3 the remote cannot be used to discretely select an input. I worked with Benchmark support to emulate this by altering several settings so that one XLR is directly selected and the other is selected by selecting the first and then sending a next input command. I have submitted an enhancement request to Benchmark to provide a mode that supports discrete inputs.

- Rich

Do you mean their remote doesn't have discrete input button? And they only have next / previous input only ?

This is very inconvenient....
 
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