Reviews

The World’s Best Audiophile Linear Power Supplies

HDPLEX 300W

Price: $685 (Quad Rail)

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About

Formed in 2007, HDPLEX Ltd. had and still has this single mission of producing high quality fan-less computer cases with minimalist design features.


Two of our prototype products, the H5.S and the H10.ODD, gained immediate recognition once they were released into the consumer market.

During the design process of our signature fan-less chassis, we found it rather hard to locate small, silent, and fan-less power supplies on the market, which gradually became a huge obstacle in creating truly versatile fan-less computer case. This turned out to be a turning point in our expansion strategy: we listened and took our customers’ feedback into consideration, and eventually we stepped into the realm of fan-less, highly efficient, silent power supply. It is now known as our NanoATX series.

The NanoATX Power Supply is an internal AC-DC adapter + DC-ATX converter combination, which is fully ATX compliant. Such combination is compact, fan-less yet rather powerful, replacing bulky and loud ATX/SFX power supply for small form factor PC. Our NanoATX Power Supply has enjoyed tremendous popularity in many SFF PC projects, such as the NFC S4.

Our first attempt is the 120W AC-DC and 160W DC-ATX combo, released in 2013.

With the NanoATX combo in place, our classic H1 fan-less PC case was introduced in 2014, to replace its chunkier predecessor, the H3 series. H1 remains the smallest ITX PC case which fully supports internal power supply solution and does not rely on external AC adapter. The H1 series also provide optional back plate for Thin-ITX motherboard.

Year 2016 saw the birth of our direct-plug 160W DC-ATX, replacing two prior models: the none-direct-plug 160W DC-ATX and 300W AC-DC with PFC adapter. The 160W DC-ATX immediately became a market leader, as it is the only direct-plug DC-ATX converter which supports PCIExpress rail and modular output. Our NanoATX product line now offers two fully passive internal power supply solutions for customers with such demands.

Our company has made a long journey and we never stop the pursuit for excellence. To commemorate our core value as well as the 10th anniversary of our company, we will soon present the 2nd Gen H1/H1.SODD and HDPLEX Cube. We look forward to a new chapter in the next 10 years.

Build & Specifications

  • Twelve Linear Technology LT3045 chips for two adjustable rails to achieve extremely low noise.
  • Hi-End Audio ELNA Super 10000µf Capacitor, One for Each Rail, Eliminating Phase Distortion
  • High Quality 300W Silent R-Core Transformer provides clean energy
  • High Precision Over-Current Protection and Over Temperature Protection Achieved by LM2904+MCU Control
  • Separated Ground for Each Output Rail
  • EMI/RFI Circuit to Prevent AC Grid Pollution
  • No Humming or Buzz noise for 50Hz and Peak load, 100% Silent
  • High Quality Neutrik XLR Connector for All Outputs
  • Low ripple noise and void of high frequency noise
  • 19V/10A XLR Output Supprt Thin ITX/NUC/Auralic Aries Mini/HDPLEX 4000W DC-ATX Converter
  • 12V/10A XLR Output Support Legacy Wavelet DAC/Qnap Nas/PicoPSU or 12V based CE device.
  • Two independent adjustable output is 3.3V/5V/7.5V/9V/12V/15V and 3AMP MAX. Each rail uses six LT3045 chips. It supports SoTM PCIE USB card/MicroRendu/Upton USB Regen/ PPA (Paul Professional Audio) USB Audio card and Squeezebox.
  • Passive aluminum chassis guarantee absolute silent and stable operation

Overview

The HDPLEX is very popular among HTPC and audiophiles alike. And for good reason. You get great sound, four outputs (two adjustable), and a single enclosure. For that reason alone, I feel like it’s worth the price of admission. The 300W kind of sits between the budget and high-end gear – but remains very flexible. For what it’s worth, I own two of these supplies and don’t plan on selling them.

The Sound

The HDPLEX 300W is one of the more organic sounding power supplies on this list. It is all about tonal intent and musicality. However, it does skip over some of the technicalities and special effects that some audiophiles enjoy. You won’t ever feel like “they’re in the room,” but it’s a raw sound with good resolution and imaging.

Brass sounds particularly descriptive with the HDPLEX 300W. Horns have riveting textures and the spatial information is transmitted wonderfully. I would say this power supply sounds more romantic than it is dark. There are clear details but it isn’t too clean. Although there is a slight edginess in the upper mids, the HDPLEX is surprisingly quiet. The blanket of warmth is overlayed in heightened sound space. This is great for appreciating reverbs and resonances in live recordings.

Tradeoffs

The biggest problem with the HDPLEX 300W is the flatter layering compared to the higher-end offerings. Everything is closer together and overlayed on top of each other. At times, the music will sound congested and clumsy. It’s not pancake flat (thank goodness), but it’s getting there.

The lack of acoustic molding is very obvious. Everything sounds more 2D and not well outlined. As such, imaging is more smeared and not very focused. It doesn’t expand or layer out the soundstage well and there just isn’t a lot of spatial clarity. Textures are a little soft and the presentation isn’t meaty enough to “feel” the music. In other words, not a very tangible sound.

Unfortunately, the bass won’t crack the floor open. In fact, it’s a bit on the lighter side in comparison to some of the other power supplies. It’s tight and textured but doesn’t protrude. That said, it does have decent slam and attack. Bass guitars and cellos don’t have that grunt and thickness to the sound – but it’s still believable.

Who Should Buy the HDPLEX 300W?

Well for one, if you need four rails, it’s tough to beat the form factor, performance, and price of the HDPLEX 300W. The effective cost is only $170 per rail!

The HDPLEX represents a middle ground where you get tonal satisfaction, sufficient detail, enough upper-frequency life, and unscathed dynamic expression. Aside from tone, it doesn’t particularly excel at anything but takes it all in stride. It’s like going to a restaurant with a B health rating. It’ll have a few violations but the food is better than some pedantic A-rated places. So for the money, I find it really hard to be too critical.

Pros

Cons

  • Ostensibly natural, warmish natural tone

  • Quiet background

  • Good resolution

  • Overall great tonal balance

  • Best value at $170 per rail


  • Imaging isn't the greatest

  • A bit of grain and roughness. So not the most smoothest or connective.

  • Not a full-bodied sound

  • Soundstage isn't very deep

  • Not very tangible.


Comparisons

vs. Sean Jacobs DC4

  • The DC4 has a much larger and meater sound.
  • The DC4 has a slightly wider soundstage
  • The HDPlex has more air and shine
  • The DC4 is in another league when talking about texture, body, and overall dimensionality.
  • DC4 sounds more real in every way, but the tonality of the HDPlex is more natural.
  • DC4 has more control and gravity…and quite a bit more bass

vs. JCAT Optimo 3 Duo

  • Optimo 3 Duo has much better layering and separation.
  • HDPLEX has more texture
  • Optimo 3 Duo has far better molding.
  • Tone is true for both in different ways. The Optimo is darker, the HDPLEX is warmer…but perfection is in the middle.
  • Optimo is smoother and quieter.

vs. Paul Hynes SR4-12

  • HDPLEX is more vivid and airy
  • HDPLEX’s tone is a little more grey-brown in comparison to the SR4-12
  • SR4-12 has heftier bass but it’s tighter on the HDPLEX.
  • The SR4-12 is smoother and more shaped out
  • HDPLEX has better resolution and has a blacker background
  • SR4-12 has much more natural tone.
  • The HDPLEX is speedier and more light-footed. But it’s rougher and leaner.
  • HDPLEX has more obvious outlines.

vs. Fidelizer Nikola2

  • The Nikola2 is meatier and more dynamic.
  • The Nikola2 is the better power supply but slightly pricier for a single rail (instead of 4)

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Jay Luong

Mr. Audio Bacon himself. An open-minded electrical engineer and software developer by trade. I have an obsession with the enjoyment of all things media - specifically in the realm of music and film. So much heart and soul (and money) go into the creation of this artistry. My aim is to find out which products get me closer to what the musicians and directors intended.

View Comments

  • Well Jay, you have only just gone and done it again. Another mammoth review. Don’t you ever sleep!?

    As a Dave owner I was lucky to obtain the first production version of Sean Jacobs DC4 and have been using that ever since with a big grin on my face every time I use the Dave. It has possibly been the biggest improvement to the sound of my system (with the possible and honourable exception of my own Wave High Fidelity STORM dual BNC cables of course!).

    However all of that is about to change because Sean has been kind enough to loan me a prototype of his new ARC6 version of the DC4 power supply. Having had the Dave all this time I was not aware of any deficiencies. That was until I plugged in the ARC6. As you say in your review the DC4 is a master at revealing the texture of instruments but now the ARC6 version has a transient speed to go with that textural information. It is a quite uncanny combination. The bass is also deeper and more powerful and yet manages to more detail and information in it at the same time.

    You will gather that I like the ARC6 upgrade to the DC4 for the Dave. It is a huge upgrade to the Dc4. I understand that existing owners of the DC4 can have theirs upgraded to the ARC6 version by returning to Sean or to one of his agents in the USA or EU.

    But that is not really why I was minded to put pen to paper in response to your review. A few months ago I did my own private shoot out of power supplies powering the Qutest. These included the Sbooster with Ultra Mk2 upgrade, Farad Super3, Allo Shanti, MCRU, Sean Jacobs DC3, PowerAdd battery, iFi, a cheap LPS from China and of course, because I could, the 5V rail from a DC4. Broadly I agree with all your comments and in the end I used the Farad Super3, not because it was the best but because it was a reasonable amount of money to spend for the performance gain with a Qutest. One thing to say about the value for money Allo Shanti is that if one has the necessary skills it takes a leap forward in sound quality if the supplied captive leads are removed from the circuit board and GX16 sockets are installed allowing after market DC leads.

    I have more recently listened again to a DC4 powering the Qutest and although first time around I rejected the idea of a single rail £4,000 DC4 powering a £1.200 Qutest as being any where near a sensible decision I have now begun to wonder whether in fact it brings the £5,200 combination up to a level of similarly priced DACs and I think it might just do that. Such is the benefit of the DC4 with a Qutest.

    So, thanks once again for the huge undertaking and it is nice of course to see you still using my WAVE STREAM cables with your Dave. 👍

    Nick.

    • I would be curious to hear the ARC6! Is there a tonal color difference between DC4 and ARC6? More shine?

      I agree, the Farad Super3 is a great value, especially if you enjoy that more liquid and smooth sound. From memory, I thought the Mojo Illuminati V3 paired well with the Qutest. And I could definitely hear the potential of the Shanti, the price is incredible for its performance (but critical listeners won't be happy). GX16 sockets with custom cabling would be interesting.

      Have you tried batteries?

  • I run my RME ADI-2 fs DAC and streamer on pure LiFePo4 cells (without any battery management electronics of course). The DAC uses 4*3.2V 20AH cells in series, and the streamer 2 of the same in series. The batteries last more than a day so I charge at night when sleeping.

    It would be interesting to know how batteries like these compares to the better power supplies.

    • Yeah, I was thinking about including batteries as well. Which specific ones would you like to see?

      • I think the more "pure" cells you use the better, and not small AA or similar batteries. Here is the ones I use:
        https://shop.gwl.eu/LiFePO4-cells-3-2-V/LiFePO4-High-Power-Cell-3-2V-20Ah-Alu-case-CE.html

        Of if you want one ready made for RME DAC, this one works (its just 4 cells in series), should be similar available in NA if that's where you live: https://shop.gwl.eu/LiFeYPO4-batteries-12V-1-1/Lithium-Battery-LiFePO4-12V-20Ah.html

        But basically you want low internal resistance in combination with pure cells. For example, a power pack used for mobile phones sounds a lot worse (they have switched DC regulators inside to get to 5V).

        It also important to stay away from "battery management", even if you risk damaging the cells if overcharged or undercharged. Those battery managements are filled with switched cheap electronic.

        I then have 18 awg OCC coppar cables with cotton sleeves as only insulation, soldered to a DC connector of copper.

          • Yes, it is. I like the sound of my LiFePO4 batteries though, and LPS manufacturers often use batteries like those as "reference" to compare with (or so I have heard).

            It's also worth mentioning that Stromtank (a really expensive HiFi power gear) uses LiFePo4 cells for their "magic", but enough of them to also drive power amplifiers.

    • Not even a Contact Us email address. Doesn't infuse confidence unless you're inside Australi and can call them.

  • great work - thanks a million!!

    comment to the Sbooster PSU: i kind of relate to your findings (using mk 1 version), adding (now unavailable) Padis fuse and Furutech Absolute Power adds LIVE to it. yet, possibly also to all other PSUs tested here

  • Hi there,
    I know you cannot review everything under the sun, but I’ll selfishly propose you review the ISOL-8 Prometheus LPSU. Their power conditioners are great and I would be curious to see how their power supply compares with the others.

    Amazing amazing review; very well done! Thank you!

  • My Farad Super 3 is custom modified, but I think it performs very well. Along w/ Jay I am factoring in price and its incredibly diminutive size.

    I am also curious about the remarks in comparison to other PSUs, which cable was used: silver or copper?

    • Listening was primarily done with the copper cable. Still great for the price, especially if you enjoy a full bodied and smooth sound.

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