Head-Fi.org › Forums › Summit-Fi (High-End Audio) › High-end Audio Forum › REVIEW: Ray Samuels Audio Dark Star solid state headphone amplifier
New Posts  All Forums:Forum Nav:

REVIEW: Ray Samuels Audio Dark Star solid state headphone amplifier - Page 4

post #46 of 372

Great review - I read it through twice. Although I'm not really interested in the Dark Star, Skylab seems able to make any topic into an enjoyable read. 



post #47 of 372
Thread Starter 
Thanks man, that means a lot coming from you, as your reviews are superb!
post #48 of 372

Hopefully more of these ship out soon.  I'd love to hear some comparisons between the Dark Star and a few other amps for powering the HE-6.  Eddie Current Balancing Act, Isabella HPA, Apex Peak/Volcano, Woo WA22, Cary CAD-300SEI and Manley Neo-Classic 300B come to mind (though I'm not sure about the last two, as I understand that driving headphones out of speaker outs on tube amps can cause transformer problems).

Edited by sridhar3 - 8/14/11 at 4:26pm
post #49 of 372
Originally Posted by sridhar3 View Post

Hopefully more of these ship out soon.  I'd love to hear some comparisons between the Dark Star and a few other amps for powering the HE-6.  Eddie Current Balancing Act, Isabella HPA, Apex Peak/Volcano, Woo WA22, Cary CAD-300SEI and Manley Neo-Classic 300B come to mind (though I'm not sure about the last two, as I understand that driving headphones out of speaker outs on tube amps can cause transformer problems).

The altest is that Ray is waiting for the chassis to start assembling the first of the 10 special priced units. I am in the waiting list for one. 



post #50 of 372

Is Apache more suitable for Sennheiser HD800 than Dark Star ?

post #51 of 372
Thread Starter 
I never had them at the same time, but I would think so, yes. The Apache is a terrific amp, and would have no problem driving the HD-800. Seems like a better choice if that is the main headphone to be driven.
post #52 of 372

Looks like Ray will receive the chassis for the first lot of Dark Star in the next 7 to 10 days. Hopefully we start seeing them in our hands soon after that... can't waitbiggrin.gif

post #53 of 372

RSA Dark Star/HifiMAN HE-6/HE-500 Whiplash Reference Mods (HE-6R/HE-500R) Listening Impressions







The focus of this review are listening impressions revolving around two different amplifiers paired up with three different headphones performing from the same, relatively high-end source gear.  The objective is to provide at least a subjective perspective on just how far the RSA Dark Star (DS) balanced solid-state amplifier could push the performance envelope driving Whiplash Audio custom-modded pairs of the HifiMAN HE-6 and HE-500 orthodynamic headphones compared to the STAX SR-009/RSA A-10 Rev A reference baseline.  This has been the only avenue open for me since I do not have any other dynamic amplifier to use as a basis of comparison.


A Word About Sources


In the age of iTunes and “unlimited” music streaming services of heavily compressed, essentially sub-FM-quality source material, the sad truth is that true reference quality source gear and reference-grade music is still prohibitively expensive.  This evaluation is conducted using one of the best digital separates available on the market today, although by no means an ultimate configuration.  Still, in terms of overall percentage, the components represent the following formula price vs. category breakdown :


Source:  40%*

Amplification 20%

Headphones:  20%

Interconnects:  10%

Power/Tweaks:  10%


* Formula factors in actual pre-owned cost, not new street pricing, which would roughly double the cost


I believe there is a huge gap between mainstream (sub-$5K and below) and Class-A (se e 2nd source link below for more info) reference grade separates in terms of sonic excellence and resolving ability of digital music at the level approaching or rivaling that of the best analog sources.  This has been debated for a long time, however, as digital studio recording technology had evolved by leaps and bounds this past decade, this technology had trickled down into the high-end audiophile market.  If you plan to attend RMAF this year, you owe it to yourself to visit the dCS, Esoteric and Zanden exhibitions for a first-hand experience.  Here at Head-Fi, we tend to focus primarily and predictably on headphones first, amplifiers at second but rarely beyond that.  The point here is that source quality is one of the most overlooked, but incredibly important and determining factor in your listening experience.




The RSA Dark Star


As a former AKG-K1000 owner and current HE-6R owner, I’ve become very excited when the Dark Star was announced in March of this  year even though details were scarce and some of its specs sounded outlandish.  Yet, during the Chicago Head-Fi Meet in May, when the Dark Star was first unveiled, I was blown away by the initial listening experience and immediately wanted one of my very own.


Since the Esoteric source gear pretty much demands a fully balanced system, including amplification, none of my previous dynamic amplifiers could match the Dark Star’s capabilities.  RSA’s previous solid state balanced amplifier, the Apache was one of my favorites, yet it was nowhere near powerful enough to effectively drive the K1000 and especially the HE-6.   I needed something that was just as easy to use with “always on” capability as the Apache, but with a lot more headroom to spare.  It also had to be reasonably compact, as my rack space is at a premium and occasionally a solid state amp like that is a lot easier to transport than, say, a B-52 or similar full-size tube amplifier.


Because of its performance curve, the Dark Star is definitely not suitable to drive high-sensitivity, low impedance cans and IEMs the way the Apache could even at low gain, however, it’s fair to say that it can safely drive most commonly used headphones on the market today above 300 Ohms.  And once in a while, when a monster like the HE-6 comes along that is so good to design an amp around it, it could prove to be a worthwhile investment.


I may be superficial, but next to sound quality, stunning good exterior looks are nearly as important to me.  Much tribute has been paid to the high-quality extruded alloy precision casework RSA uses and it’s everything cracked up to be and more.  C&C work and commodities are expensive, but the results are gratifying to experience from every angle, each switch and knob responds with a reassuring click.  The Dark Star simply exudes quality and workmanship.


front shot.jpg


RSA amps have always been some of the quietest out there in terms of operating noise.  The noise level of the Dark Star is non-audible, despite all its power regardless of gain setting employed.


Finally, I would like to emphasize the other key ingredient behind RSA’s success.  It’s post-sales support, which is among the very best I’ve personally experienced in this business.  Whether it’s today or two years after the sale, Ray Samuels stands behind his products.  Case in point, even Plitron transformers fail from time to time--as my A-10 PSU can attest--and the unit was repaired within 2 days of receipt and back before the end of the week sporting a brand new transformer, accompanied by no less than three separate follow-up emails.  Can’t ask for more than that.




Source Gear:  


Esoteric P-03 Transport+D-03 DSD DAC+G-0x Master Clock.  D-03 configuration is set to Redbook DSD upsampling (where applicable), all filtering OFF.  G-0x master clock frequency: 176kHz, set as an external reference clock master signal to both P-03 and D-03.  Whiplash Audio Reference Coax interconnects used as BNC clock signal sync cables.  Dual Frost Audio BlackFrost AES/EBU XLR digital DSD interconnect prototypes deployed between the transport and the DAC.


(Additional references, design highlights and internal pictures of this source package gear can be found at http://www.6moons.com/audioreviews/esoteric4/trio.html and here (January, 2011 Update))




Reference Baseline:  RSA A-10 Thunderbolt II Rev A fully balanced electrostatic amplifier.  Rev A mod includes upgraded capacitors for enhanced synergy with the Sennheiser HE-90 and STAX SR-009 ear speakers, as well as higher capacity SB fuses to handle the increased output from the 1959 Mullard NOS 10M 12ax7 input stage tubes vs. the stock Telefunken tubes, which produce a more detailed, but overall less musically involving sound signature.




RSA Dark Star solid state fully balanced dynamic amplifier.  (Additional reference:  RSA website or Skylab’s excellent review at the beginning of this thread).





Reference Baseline:  STAX SR-009, Japanese version.  Manufacturing date:  July, 2011.




Whiplash Audio Modified HE-6 Reference (subsequently referred to for the purpose of this review as the HE-6R and HE500R for brevity.)  Modifications include hardwiring thru the housing using TWag V2 Reference wire, custom shielding and dampening, installing custom-manufactured dampening rings and upgraded internals vs. stock.  Completely bypassing the low-gauge stock RF headphone connector has allowed fully balanced wiring implementation as well as the implementation of monolithic end-to-end wiring minimizing signal transition between different conductors along the signal path.  Although the HE-500R doesn’t have the same power requirements as the HE-6R, it does benefit from the high-quality direct wiring equally as well.  Both headphones now feature the upgrade leather ear pads from HifiMAN, resulting from enhanced isolation compared to the legacy velour ear pads and in case of the HE-500R, added stability due to the higher density foam applied.




Analog Interconnects:


Frost Audio BlackFrost Crystal Core Reference XLR3 balanced interconnects


Power Components:


PS Audio Power Plant Premier, PS Audio Premium AC-Receptacle Upgrade.  Frost Audio BlackFrost AC cables




Townshend Audio Versatile Seismic Sink Stand (Reference:  http://www.ear-usa.com/townshendsinks.htm)



Test Methodology:


Each of the following test albums have been evaluated in the following order:


  1. SR-009/A-10
  2. HE-6R/DS
  3. HE-500R/DS


Input switching required alternating the receiving end of the BlackFrost XLR cables from the A-10 balanced input socket to the corresponding DS input socket between steps 1 and 2 and performing the reverse between each subsequent rounds.  Prior to the initial tests, volume output matching has been performed using the Decibel Meter Pro 2 iOS utility from Performance Audio running on an iPhone 4.   Inside cup pressure for all three headphones have been set to approx. 80dB-A weighted average.  This had translated to the following volume pot settings:


  1. SR-009/A-10 - 12 o’clock position
  2. HE-6R/DS - one step beyond 12 o’clock at High Gain setting
  3. HE-500R/DS - one step below 11 o’clock at Low Gain setting


Listening Impressions By Genre


Electronica/New Age:


Bella Sonus' Enamoured album is one of my perennial reference recordings used to test rich, layered confluence synth foundation elements intermixed with acoustic instruments and eerily beautiful female vocals.  One of the many hits, "Rincon de Espana" poses some unique challenges few headphone systems are capable of rendering with respectable degree of authenticity.  Typical shortfalls, such as mixture of overly bright treble, artificially elevated bass and incoherent imaging without the proper depth can severely compromise the overall listening experience of this recording.


The HE-6R/Dark Star combo has managed to nearly completely avoid these pitfalls compared to the A-10/SR-009.  Despite the higher density leather ear pads, the presentation projected a very convincing replica of the electrostatic rig in most aspects.  Bass energy and texture was robust without being obtrusive with clean instrument separation.  Midrange rendering--not normally a signature trait of the HE---had just the right amount of emphasis to my ears, as demonstrated by the natural attack and associated decay reverberations of the congas.  The biggest differentiator was a hint of sibilance not present in the SR-009 rendering when it came to female vocals peaking around an estimated 15kHz.  Considering the SR-009’s rendering to be the more accurate, the HE-6 treble brightness--although somewhat muted when compared to stock--is still present.  The effect of this, however, could be both a curse as well as a blessing depending on source material.  All in all, each A/B switch between these two systems had reinforced the my earlier conviction of just how great sounding the Dark Star/HE-6R combo can be when fed from a reference quality source.


Switching to the HE-500R essentially had a similar overall effect as if the Dark Star was somehow transformed into a high-quality tube amp outfitted with premier NOS tubes.  Remarkably, the magical flamenco guitar riffs and piano accords have become less transparent but somehow more natural and--dare I say it--often more charming and engaging.  The HE-500R in this revision is still mid-forward, but not obtrusively so and compliments the relatively linear sound signature of the Dark Star.  The treble energy is considerably less here than with the HE-6R, but that actually helps here in certain passages to sound overall more organic, in others it rolls of just a bit shy where it should be especially when contrasted with the HE-6R and even with the SR-009.  Still, adding a dampening ring to the HE-500 does yield considerable benefit to the overall listening experience primarily in increased imaging precision due to the decreased harmonic resonances between the driver and the inner wall of the housing.






One of the genres typically rendered in a superior fashion using electrostatic gear is female vocals with an acoustic arrangement primarily because of the enhanced treble extension and resolution of the design.  While this is a generalization, it also happens to be true and the question becomes just by how much these latest generation planar magnetic ear speakers close the gap when properly amplified.  Jennifer Warnes has been one of my favorite singers for some time, and her 20th Anniversary 24K Gold Edition remasters have certainly gone a long way to secure a permanent spot on my playlists.  "Bird on the Wire" located on her signature album "Famous Blue Raincoat" has been essentially revitalized to reference quality status in my book.  Since the album is fairly devoid of synthesizer compliment, I was looking forward to comparing the strengths between the superior overall resolution of the HE-6R vs. the seductive midrange of the HE-500R when it comes to rendering analog instrumentation.


Compared to the SR-009/A-10 baseline, the HE-6R did not disappoint.  In keeping with the "RSA house sound" signature, the combo managed to faithfully deliver an impressive performance.  The opening kick-drum sequence was majestic and powerful without obstructing the sparkling chimes seemingly appear out of nowhere, linger in space and disappear with just the right amount of decay.  Lower midrange reverberations did not have quite the the complex texture and musicality of the SR-009's rendering, however, this required a few tries to pinpoint.  Jennifer's voice still had the same mesmerizing quality and air.  Soundstage and depth were roughly on par as well, highly localized and consistent.  In this recording sibilance was far less evident with the HE-6R.  The STAX had delivered its usual, studio monitor-quality rendering with laser-like precision.  


Convincingly rendering analog instruments is a somewhat limited exercise in futility even under the best of circumstances for prerecorded music vs. live performance.   Part of the reason why the SONY MDR-R10 has been held to such high regard is its amazing midrange performance.  The HE-500R has a somewhat similar quality in adding a touch of emphasis to those octaves where the body of the music lives.  It's that musicality that sets it apart from both its bigger brother and especially the SR-009.  The musical arrangement of this track had the sweetness one associates with the sensation of "being there" with the musicians as they play.  Even though I have consciously understood the HE-6R to be a superior performer, the HE-500R had somehow managed to render “Bird on the Wire” more fun to listen to.  Call it an emotional attachment or personal preference.  It doesn't really matter, as long it's about the listening experience.  Part of that experience is the authentic rendering of the lead and backup vocals.  That is where the HE-500R had taken the back seat due to the above noted treble rolloff, which managed to subtly alter Jennifer's voice compared to the other headphones.  The effect was more akin to inserting a veil between the singer and her microphone, which was simply not there before.  It was still thoroughly enjoyable and natural, and would not have been evident if not for the ability to be able to alternate between these different headphones.  If there was a way to fuse the midrange of the HE-500R into the HE-6R, the comparison between this imaginary model and the SR-009 would have been much, much more challenging, especially to declare a personal favorite.


Hard Rock:


Univeral Music of Japan has cost me quite a bit of money during this past year, primarily with their excellent SHM-CD and some of SHM-SACD remasters of my favorite albums of the 70s, 80s and beyond.  Slash's self-titled first solo album is one of the new releases they've done an amazing job bringing it all together for me.  An appropriately labeled 2CD/1DVD "Super Deluxe Edition" (UICE-9088) with a matching price tag is an ultimate way to experience this all-star cast performance if you're a fan of this genre.  As much as I had thought that the SR-009 rig would easily take the top spot for preferred listening across the board, I could not have been more wrong.


Rock and blues music does have unique characteristics.  Hard rock, especially tends to be more aggressive, bombastic and best served on a system capable of high-energy delivery brimming with dual mid-bass/mid-range peaks as opposed to a "proper" audiophile reference frequency response curve one associates with studio reference monitors used by recording engineers during mastering sessions.


Listening to this album using the SR-009 and even the HE-6R proved to be counterproductive.  Consciously I was aware that I'm hearing the best possible rendering of the recorded content.  Nothing was lacking, every aspects of the music had been faithfully delivered, but there was no emotional attachment; tapping of the feet or bobbing of the head.  Sterile, Ultra-Fidelity delivery all around. Great.


This had all changed when the HE-500R entered the picture.  Percussions, bass guitar and electric guitar riff pitch attenuation and subharmonics have transformed into a more natural flavor.  Suddenly, it felt more like a live performance filled with adrenaline that reminded me what it was like to listen to this type of music 20+ years ago and being carried away.  With the mostly male lead vocals, extended treble resolution became an afterthought, in fact the HE-500R treble performance seemed perfectly in harmony with this music, even during Rihanna's "Beautiful Dangerous."  Similarly, the HE-500R's instrument separation--which is a subset of both the HE-6R and especially the SR-009--has become an advantage since we are not talking about complex compositions involving a dozen or more instruments here in a layered accompaniment.  This is good, old-fashioned hard-rock and it doesn't have to apologize for what it is.  


Note:  it would be, of course, relatively straightforward to on most digital systems to take a parametric EQ and make some slight adjustments to the HE-6R's sound signature to make its sound similar to the HE-500R.  This is not an option for the Esoteric D-03 DAC, which doesn't feature this capability.  Also, the Sennheiser HE90 is much better suited--at least when paired with this particular A-10--to tackle this kind of genre and deliver what I came to appreciate to be a "best-in-class" performance as opposed to the SR-009, which excels in other genres.




Outside of orchestral classical music, smooth Jazz is certainly one of the most demanding genre to render with any kind of authenticity.  Subtleties and resolving ability  trump most other considerations...of at least that is how I think conventional wisdom holds.


At first blush...er, initial listening, the SR-009/A-10 is clearly a cut above, as well as you would expect given the price difference (the SR-009 alone would buy you a Dark Star AND a HE-6R on  a good day).  Switching to the HE-6R, however, has the smallest delta out of all these genres.  Diana Krall's "When I Look Into Your Eyes" 2011 remastered, single-layer DSD SHM-SACD (Universal, UCGU-9006) is a revelation when played on the Esoteric P-03/D-03/G-0x source gear, easily superior of the 24/96 PCM version recently released by HDTracks.  The extended dynamics are carried over equally well, and the pitch of Diana's voice sounded just about the same as well. Crystal clear transients with nary a sign of any sibilance.  The strum of guitar accompaniments in "I Got You Under My Skin" resonated with just the right amount of attack and decay without impacting or suppressing any other supporting instruments such as the piano and violins.  In fact, an extended listening session was needed to try to differentiate the HE-6R's performance.  It essentially came down to longer-term listening fatigue involving the usual treble brightness.  I have come to the conclusion that the HE-6R--at least to my ears--as enjoyable and impressive in the beginning grows a bit tiresome over time, which never happens with the SR-009 as it seems to somehow manages to maintain just the right amount of tonal balance across the entire audible spectrum.  I'd like to emphasize again that I'm well into the nitpicking category here, however, at this level of sophistication those subtleties can be a deciding factor when favoring one particular system vs. another, according to personal preferences.


The downside of extended listening sessions during a controlled A/B comparison testing is that the brain--in my case whatever's left of it--gradually attunes to each sound signature over time, making even these subjective comparisons less credible.  Regardless, the HE-500R coupled with the Dark Star has managed to convey more of the analog beauty and naturalness of the musicians' performance, at least as far as the instruments were concerned.  The synergy between the HE-500R and the Dark Star has yielded a similar sonic profile that was more akin to a HE-6 being driven by a powerful enough tube amp.  One of the typical tradeoffs between tube and solid state amps is that depending on the implementation, tube amps tend generate a more relaxed sound signature.  This obviously doesn’t apply to modern solid-state amps such as the Dark Star, which actually mashes well with the HE-500Rs, which typically tend to perform a bit slower than the HE-6R.  The gap was not as pronounced here as much as it tends to be when paired to less powerful amps.  Needless to say, the combination was highly enjoyable and rewarding to experience again and again.




In Closing



During the weeks before the release of the first iPad and even shortly after that, pundits decried it to be nothing more than an oversized iPod Touch.   Obviously this sentiment turned out to be an oversimplification of a hugely successful device that since carved out its own market segment by opening up so far unrealized possibilities to developers by making use of the bigger screen estate that was not possible on on the Touch or the iPhone.  Building on the success and the high-level design principles of the amazing SR71B portable amplifier, the Dark Star is a speciality desktop headphone amp designed to drive even the most demanding ear speakers and headphones with power to spare, straight from an XLR4 or dual-XLR3 sockets without the use of clumsy adapters connected to the back of speaker terminals of vintage receivers and power amplifiers.  Unlike the iPad it had never intended to be a mass-market product; rather to serve a niche market by catering to those who need gobs of power in a reasonably compact package. The modified HE-500 and especially the HE-6R is definitely capable of harvesting this capability and perform at a level at least commensurat--if not a cut abov--their asking price.  As an added bonus, an extremely sharp casework that looks perfectly at home next to $15K Esoteric solid milled aluminum separates and all of a sudden you’re looking at a great combo and a solid investment.

post #54 of 372
Thread Starter 
Wow! Good stuff.
post #55 of 372

Nice review.  I really do like the silver better than the black in the case of the Dark Star.  Too bad the A-10 didn't come in silver as well.

post #56 of 372
Originally Posted by project86 View Post

Great review - I read it through twice. Although I'm not really interested in the Dark Star, Skylab seems able to make any topic into an enjoyable read. 



X2, Well said p86.


Another terrific job Sky !!!


Tip of the hat to Warp for an equally excellent job !!!



Edited by Pricklely Peete - 9/25/11 at 7:32pm
post #57 of 372

Nice Job.


This statement in your review about sums it up for me."upgrade leather ear pads from HifiMAN, resulting from enhanced isolation compared to the legacy velour ear pads"


What this tells me is that the DS has the RAS house sound, what I call a wall of sound 2D like sound field.

Reason for me saying this is because I have both the HE6 velour and leather pads from HiFiman for my HE6's, and imo the new "leather pads" has what you call "enhanced isolation" form ambient noise (I guess) but at the cost of the wonderful depth the HE6's with the deeper/detail layering velour pads has to offer, a 3D like sound field.


Thanks for your nice write up, I guess I can pass on this amp.

post #58 of 372
Originally Posted by Audio Addict View Post

Nice review.  I really do like the silver better than the black in the case of the Dark Star.  Too bad the A-10 didn't come in silver as well.

I wish for that as well.  This particular A-10 was Ray's show demo unit which I've bought off of him during last Summer's NC Can Fest.  It has since been upgraded but the chassis is the way it is.  It's horribly expensive to produce, probably the most expensive of all the RSA amps because of the complex extrusions.  Still amazing to behold and has great synergy with the HE90s since the upgrade and does a very good job with the SR-009s as well.


post #59 of 372

In our last Detroit meet in June when Ray brought the DS with him Jude had a pair of SR-009 and the Woo WES there too. I tried the SR-009 which in my opinion are far better than the OS-2. I was able to made a comparison of the SR-009 driven t=by the WES and also by the A-10 and INO the sound out of the A-10 if clearly superior. The A-10 is an incredible amp and if I ever go to electrostatics rig that is the only amp I would buy.


Just got an email from Ray. He will be offering the DS in both colors and he mentioned he is still waiting for the chassis.

post #60 of 372

That's a REALLY pretty cmoy! Nice review, Sky!

New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: High-end Audio Forum
Head-Fi.org › Forums › Summit-Fi (High-End Audio) › High-end Audio Forum › REVIEW: Ray Samuels Audio Dark Star solid state headphone amplifier