DanaTone Head-Space Solid State Headphone Amplifier


Headphoneus Supremus
The Dana Tone Head-Space Solid State Headphone Amplifier Tube and Transistor Sound Converge?
Pros: 1. Appears well built from good quality materials externally. 2. Enough power for the likes of Susvara (possibly my next HP addition) on high gain and the likes of Utopia will be safe on low gain. 3. Some unique circuit features allowing “tuning” of the sound to suit.
Cons: 1. 1 year parts and labor non-transferable warranty. 2. Expensive
HP Amplifier Shootout: June 5 thru 13, 2021

DanaTone Head-Space vs. XI Audio Formula S + Powerman vs. RAAL HSA-1b

Note: I am not a professional reviewer, or an electrical engineer, and I did not earn my living working in audio. I’m just someone who’s been involved in the hobby since 1970 and I do this for fun. If you want my final thoughts on the comparisons skip right to the summary at the end. My music preferences, especially for evaluation purposes, are about the sound of acoustic instruments and classical music.

Thanks to Vinh Vu of Gingko Audio who distributes the Danacable line of digital, headphone, IC, power, and speaker cables, I’ve had the opportunity to spend a few days listening to the DanaTone Head-Space headphone amplifier. I started a relationship with Vinh several years back and have purchased a number of Danacable IC’s and HP cables from Gingko Audio (owned and operated by Vinh Vu and Norm Ginsberg). Gingko’s offerings also include a number of isolation and vibration damping accessories, a line of speakers, and a few other audio related products. Danacables are designed and manufactured in Colorado by Dana Robbins, who also developed the Head-Space which will be marketed under Clarisson Audio, also owned and operated by Vinh and Norm.

Dana Robbins, the man behind Danacables, has been working on his Head-Space design for several years and some specs, reviewer impressions and other info can be found on the Clarisson website.




Some of the features of the Head-Space include: Class AB push-pull in an all discrete transistor design. Fully regulated independent power supplies, proprietary selective feedback technology, and a unique output topology.

Having some time to prepare I spent the previous week to 10 days comparing my Formula S & Powerman (abbreviated S&P going forward) that I purchased along with the Phi 11/2018. It’s a Class A, BJT design that was used to voice the Abyss 1266 line. My RAAL HSA-1b was purchased 1/2021, another BJT design and Class AB (I think) designed especially for the RAAL SR1a but with features to allow use with any HP type except electrostatic designs. Both have the power capability to drive any other type HP I’m familiar with. The 1266 Phi and HD800S will be the two HP’s I will evaluate the Head-Space with. (If you don’t own or plan to own an SR1a or have a need/use for the amp outputs the HSA-1b probably doesn’t make a lot of sense in that there may be other good sounding HP amps below as well as above the HSA-1b’s price point. If you own the SR1a and have other phones as well, the HSA-1b could be a better proposition as funds could be directed at other phones instead of multiple amps. There is also the space savings too.)

It shouldn’t be a surprise that the Formula S&P/1266 and the HSA-1b/SR1a combos complement each other’s sonic characteristics so well being developed in conjunction with each other. The smooth, warm sound of the HSA-1b and the more neutral character of the Formula S&P are well matched to their respective phones and seem to bring out the best with their partnering HP’s, especially at the frequency extremes. I purchased the Powerman at the same time as the Formula S and have spent virtually no time at all listening to the Formula S without the Powerman. It didn’t take me long to determine I preferred the Formula S with the Powerman and stopped thinking on it. I suspect the improvement with the Powerman may be that the Formula S is Class A in operation (where the Head-Space and HSA-1b are Class AB). Both the Head-Space and HSA-1b have done a fine job driving both my 1266 Phi and HD800S.

The HSA-1b currently lists for $4,500US. The XI Audio Formula S ($3,499US) with Powerman ($2,99US) will set you back $5,898US. The Head-Space is $8,995US (MSRP).


Back in the 1970’s I remember more easily noting differences between the sound of different manufacturers tube and solid state gear; Dynaco vs Marantz vs ARC with tubes, Dynaco vs McIntosh vs Carver (Phase Linear 400) with solid state, and so on. My ears were much younger then too! Over the passing decades it seems to me that continual refinement of tube and SS designs has been heading towards a convergence in sound with a goal of accurate reproduction with respect to sonic outcomes. There is still a fairly significant difference in sound that I hear between tubes and SS amplification but even at that the lines are sometimes blurred for me with the hybrid tube/SS designs. Of course they don’t all sound the same, and rarely are they radically different, but tube designs bring a touch of richness to the sound especially in the mid frequencies, and SS designs exert more control and extension at the frequency extremes and a different type of transparency (with usually less warmth) in the midbass and midrange. Either amplifying device type or any circuitry can probably be massaged a bit with design and choice of parts in an attempt to exhibit sound characteristics of the other type with voicing per the designer’s goals.

Regardless of the amplification devices used many of today’s designers seem to be able to get the best out of their chosen amplification devices whether they are tubes or FET types or BJT types, producing very enjoyable listening experiences for me.

This is not to say they all sound alike but it’s getting harder for me to ferret out “significant” differences in the price bracket I play in for audio and the different amps and HP’s I’ve been able to own and evaluate. Others may hear it differently and personal biases/preferences, of course, always play a role. I’m not married to any one amplifying device (tube or transistor), circuit design (all tube, all SS, or hybrid) or operating class mode; it’s about the end result of how it sounds to me. And also for me it’s often about finding the right amplification to match up with my various chosen headphones I’m currently using. And rarely does one size fit all, but it may fit several.


Of the 10 different headphone amps I currently own for the comparisons (1 rig upstairs, 1rig downstairs) with the Head-Space I chose the Formula S&P and HSA-1b thinking they might be most similar in some aspects of the builds as I compare specs, circuit design features and prices per the info on the respective manufacture’s websites. Not exactly scientific but that’s about the best I can manage. All three are pure solid state designs. Both the HSA-1b and Head-Space (optionally) can provide the ability to drive high efficiency speakers as well but I won’t be addressing their use with speakers and have no plans to ever use them that way.

Both the Formula S&P and Head-Space are SE only designs and while the HSA-1b offers both SE and balanced I will use it only on the SE input (with my LOKI and the extra cabling “removed” from the SE run) and other switches in the appropriate position for conventional HP’s or in the case of the 1266 with HSA-1b I will also try the adapter for the high current output. I will use the 4 pin XLR outputs on each amp for connectivity. I also will use 1 meter runs of JPS Labs SC-V IC’s with the Formula S&P and Danacable Reference II IC’s with the Head-Space between Yggdrasil 2 and the amps. Time permitting I plan to substitute 1 meter runs of CFL’s Mogami Neglex 2549 Microphone cable using Neutrik NF2C-B/2 Pro RCA connectors on all 3 for final comparisons and to eliminate any variables that might arise from using say 3 different designs of IC.

As my Yggdrasil 2 has only 2 SE outs I will run one of them thru a good quality 4 way RCA switchbox so I can change the signals to each of the 3 amps easily and quickly without having to make any other changes other than to move the headphone’s 4 pin XLR connector to the chosen amp. If any knee-capping of the sound occurs due to the use of the switchbox it will be an equal disadvantage to all 3 amps. Again and time permitting I will also compare just 2 amps at a time using direct runs from the Yggdrasil 2 with the amp manufacture’s chosen wire. My 1266 Phi and Sennheiser HD800S will be the headphones I use with Danacable Nirvana and Lazuli for the amp to HP cabling on the respective phones. I also have Moon Black Dragon’s for both phones. A lot of ambitious “ifs” here.

The SR1a is a horse of a different color altogether and can only be driven from its specialized output on the HSA-1b or my JOT-R (or conventional power amps) so obviously I couldn’t use that in my amp comparisons. I chose the Senn HD800S not because it bests the 1266 Phi (or my #1 HP the SR1a for that matter) but it does image and set a sound stage well enough and it’s light weight with no fidgeting with placement on my head and can be easily driven by the available power from each of these three amps as can the 1266 Phi. I also have an HD800 on hand as well. Past HP’s I’ve owned with higher-fi pretentions include the Senn HD600, Oppo PM-1, and Utopia. All sold at this point, but I do wish the Utopia had come with a slightly larger ear cup opening, I really liked the sound and in many parameters it made a nice contrast to my other phones.

AC cables will be Pangea14 (and alternately, the DanaCable Power Source with the Head-Space) connected to a Furman Elite 15 PFi spike, surge, and filter unit.

The last piece of the setup is matching volumes, easy enough to do with my SPL and a 315Hz test tone. I always have to set the HSA-1b’s stepped attenuator first and then adjust the Formula S and Head Space to match which is easy to do to a precise tenth (0.01db) thanks to the high quality volume controls used in both amps. I turn on all 3 amps in the morning and turn them off at listening days end. I found that in use and temperature wise the HSA-1b runs almost cold / room temperature, the Formula S&P runs warm to the touch but I can place my hand on the heat fins after 8 hours on without any discomfort (makes sense being a Class-A design) and the Head Space runs somewhere in between the other two.

Being CD only for source and in light of varying recording levels of the demo music on my chosen CD’s requires occasional resetting of the volume to keep from either stressing the phones or my ears, or ending up listening at such a low level that the sound ends up washed-out like elevator background music. In my experience different recordings want to be listened to at different volume levels to bring them to a life-like level and this can vary from CD to CD. My evaluation CD’s include the Chesky Ultimate Demonstration Disc, some classic rock, and mostly a lot of classical (my primary meat and potatoes) of varying recorded SQ’s and for all size ensembles from solo piano to 100 piece orchestras.

The point of all this was to try and get to the sound of each amp on an equal basis by keeping all the other parameters as identical, most of the time, as I can. Of course I couldn’t help but try using the amp manufacturers recommended cabling.

Note: The case work, front panel trim, and heat fins for both the Head Space and Formula S appear to be identical with the exception of the faceplate and rear plate being laid out differently and the finishes, mat black vs brushed aluminum. Dimensions and weights for the amps seem close to identical as well.

And so,

Sometimes the planets align just so and all is right in my world. Serendipitously, today (6/4/21) Vinh had business at a location near me and I had an appointment as well so we met at a pre-arranged location and Vinh hand delivered the Head-Space to me giving me the opportunity to meet him personally, and his wife Mai, and “chew the fat” a few minutes. Genuinely nice folks.

In addition to the amp Vinh supplied a 1.5 meter pair of Danacable “Diamond Reference” IC’s, a 1 meter “Source Clarifier” AC cable for source components and a 2 meter “Power Source” AC cable for the amp. There is a serious amount of wire under the sheathings but they are still very flexible with very heavy duty and heavy duty connectors at both ends.

Also included was a Danacable TruStream USB cable but I can’t make use of it being CD only for my source. (The transport was a NuPrime CDT-8 feeding its AES output to my Yggdrasil 2). These are some of Danacables top of the line goodies and I am looking forward to using these drool worthy cables with the Head-Space along with JPS Labs cabling for the Formula S/P I already own, as well as my CFL Mogami 2549’s.

This Head-Space unit itself came in the “headphone only” amp configuration version, so the rear panel layout is a little different from the website info/pics (listed on page 1) which shows a picture of the HP/power amp configuration. The 110/220 switch was already set for 110. There are individual L & R channels, two position push buttons on the rear panel of the Head-Space for selecting low (in) or high (out) gain. I did notice some low level electronic noise in the high setting but It was dead quiet on both phones with low level and the fact is I don’t feel either phone really needs that much juice for the listening levels I like. I never had to go above 12 o’clock on the volume knob with either phone on the low level setting. There is also a knob on the rear panel to adjust the brightness of the blue lighting behind the volume control knob on the front panel. I like the look of that front panel with its front of plate mounted, “locking”, ¼ inch and 4 pin outputs. Again, the amp is SE only and the 4 pin is there for convenience, but it also allowed me to go with 4 pin headphone cable connector’s on the 3 amps (leaving the XLR/RCA switch on the HSA-1a in the RCA /SE input). I like to use 4 pin whenever possible, the balanced vs unbalanced signal not being important to me but I do like the physical aspect of the fatter XLR barrel.

There was also a brief manual included that is worth a read.

I begin,

When a new piece of gear gets installed into one of my rigs I always anticipate a parting of the clouds with God-Rays hitting my ears.


Never really happens but….

This Head-Space unit has probably spent many hours in operation with a number of other listeners so I have little doubt that it is fully broken in.

Well, the first 4 days were fun, but new toy syndrome coupled with using the different cabling options (Danacables on the Head-Space, JPS Labs for Formula S&P, CFL Mogami 2549’s on the HSA-1b) yielded good results on all 3 amps but had me wondering if I was hearing each amp on equal footing. So, with day 5 starting I replaced all cabling for the Head-Space and HSA-1b with my familiar old CFL Mogami Neglex 2549’s and for uniformity, Pangea 14 to supply AC power to all 3 amps.

Note: What follows is my attempt to describe what in many instances are small differences in sound between these 3 amps that are noticeable and meaningful to me, but maybe not to others.

Once all 3 amps were running on the same cabling I think I was able to make more progress in comparing them. Doesn’t make sense to me, cables don’t make a difference, do they? (Sarcasm mode: “ON”. Let each listener decide that for themselves). I set my HSA-1b to 0 db gain when I received it and I wasn’t about to pop the lid to adjust the various gain switches. When I switched from low to high gain on the Formula S&P and Head- Space and made adjustments with the sound level meter I discovered just how powerful the Head-Space is. I had to turn up the volume on the Formula S&P a little; I had to turn down the volume on the Head-Space. I’d say it has plenty of power in reserve and may likely handle power hungry phones like the Susvara well (most likely my next HP addition).

Methodology was always the same. A few years back I got tired of juggling 2 dozen plus different CD’s and their jewel boxes, so I burned a playlist making 8 CD’s of excerpts (mostly classical) from these discs to simplify and speed up the process. So I’d play a track on the Head-Space, the same track on my HSA-1b, then on my Formula S&P, and then again on the Head-Space to confirm my thoughts and make notes.

Now, to get to the heart of the matter, the Head-Space is one beautiful sounding amp. Regardless of what cable combinations I used I could always hear something special in the midrange; a transparency with body, “there-ness” (for lack of a better word.) The HSA-1b had a bit warmer, thicker sound (that I think complements the SR1a perfectly). The Formula S&P has a cooler, “see thru” type of transparency. (Always difficult finding the words to relate my listening takes when describing sounds).

Per Vinh, with the Head-Space that midrange is the result of the Adaptive Damping Factor (ADF), a technology that allows for the ability to “tune” the sound even to a customer’s specific listening preferences, although I don’t know how that works. I suspect this is done during the build, it is most likely not a user adjustable feature from inside the case. But, with ADF the amp can be tuned to make the mids lusher, the bass tighter, the top end more extended, and so on. This may also have a bearing on the cost of the Head-Space factoring in the variables of customization to produce a specific sound to suit.

The ADF setup on the Head-Space I’m listening to seems to deliver the most tube-like sound in a solid state amp I’ve experienced yet but the bass is still nicely detailed, full, and deep ranging as well.

The mids on the Head-Space sounded a hair more forward than the Formula S&P and closer to the HSA-1b in nature but with none of that “in my face” perspective on it (or the HSA-1b) that I’ve gotten with some other amps with a bold midrange. With the Head-Space I hear the bass as having a little more “grunt” to it and the highs are detailed without an exaggerated edge, highs do have a tube-like smoothness. Imaging is as pin-point as the other two amps. The Head-Space Images are perhaps a bit better sculpted or rounded dimensionally and the sound fields depth and layering are presented as well as the recording captured it. But perhaps the Formula S&P is a hair better with depth at times and maybe that is also a characteristic of how the ADF is set up on this amp. I think the center fill between the channels is a hair better with the Head-Space. The L/R spread is equally wide on all 3 amps with either my HD800S or 1266 Phi.

(Note: In my experience amps combined with HP’s that have dips in the mid frequencies tend to convey an illusion of more depth to the soundfield, amps combined with HP’s that have a bump in mid frequencies display a shallower soundfield. But it’s much more complicated than that when you factor in the source recording and what the engineers / producers wanted to convey and captured).

This is certainly one of the most interesting solid state amps I’ve listened to, to date.

On to some specifics:

Some listening examples from the Chesky Ultimate Headphone Demo CD.

While I don’t often listen to these genres I find the smaller size ensembles and impeccable recorded sound quality a tremendous aid when I do comparisons of audio components so I rely on the material on this CD often.

I also want to reiterate, these differences in the sound of these amps are not day/night, or any other statement of exaggeration. These are 3 top notch performing amps and personal preferences from a variety of perspectives could vary. You want day/ night differences, compare headphones or speakers. The interaction of a given amp with a given headphone or speaker (and yes, their connecting cabling) can make a bigger difference (in my experience) because of so many variables.

When the Saints Go Marching In: With the Head-Space the tuba and drum solos sound layered better with the instruments in front, and a bit closer together center fill-wise with the tuba and drum set, which I find to my liking. There are slight variations in depth but image placement is similar and exacting on all .

Don’t You: With the Head-Space the cello has more “grunt” in the low notes, by that I mean the texture of the sound of the bow hairs rubbing on the strings. Also, I hear the hand slaps on the conga drum deliver more of the sound of skin hitting on drum head. Amber Rubarth’s voice and guitar are stable and on center.

Las Perlas de Tu Boca: The Head-Space and HSA-1b brings the singer’s voice a little closer than the Formula S&P but I like it either way. Fortunately that forward quality never becomes “shout-y”. Intelligibility of the words is good on all 3, what I hear with the Head-Space is that 3D roundness I mentioned earlier, to the voice. This is a quality I notice time and again with the Head-Space, roundness to the instruments and voices that is highly reminiscent of what some of my favorite tube gear delivers without having to fuss with tubes and tube selection or deal with tube aging issues, and in today’s market, the prices of some. It’s not identical to tube sound but a step in the right direction and who’s to say but that it might be more true to the recording.

Ben’s Farm in Vermont: The Formula S&P displays a little more depth than the other two. Again, the Head-Space and HSA-1b sound a bit more “present”. The bass drum strike that closes this is solid on all 3 with the right amount of reverb.

WaWaWa: again, the various voices are a hair closer, more present on the Head-Space and HSA-1b, sound stage depth a hair better on Formula S. The guitar solo stands out a bit more on the Head-Space and HSA-1b as well.

War: This is a fun exercise for percussion instruments and a test of transient attack and decay. The Head-Space seems to put a little more air around the drums and bell like sounds.

Various selections from my classical collection.

Shostakovich / Shchedrin: Piano Concertos on Hyperion CDA 67425:
The piano key strokes are nicely articulated on all 3 amps with the HD800 or 1266 Phi, but my SR1a on the HSA-1b is noticeably more realistic sounding to my ears simply because the SR1a’s transient capabilities, attack and decay, are superior, but that’s a comparison between the HP’s not the amps. The overheated mic placement of the piccolo in the closing bars of the first movement is ameliorated a bit with the Head-Space making for a less ear piercing hearing. Now this points up the question of accuracy versus listenability. The Head-Space with its tube-like top end often made a positive difference for me given the variables in even high quality specialty recordings, especially in the high frequencies.

Shchedrin: “Carmen Suite” / Pletnev DG471136: Interesting composition for a large string orchestra and just about every orchestral percussion instrument there is; no horns, no woodwinds. Without woodwinds, and especially no horns inter-modulating with strings it allows for excellent clarity of tones. This is a good test of the entire frequency spectrum, transient attack and decay, and capturing the ambience of the recording location. The slightly dry acoustic makes everything standout, from the opening and closing bells backed by softly played strings, to some really strong tympani and other percussion instrument attacks. Plenty of air and impact with the Head-Space and that 3D effect it has with individual instruments. Both the Formula S&P and HSA-1B do a great job as well but I lean towards the Head-Space.

Gregorian Chants: Teldec 4509-96036-2: This recording was made in1966 (CD released 1994), an all tube recording on the Telefunken label. The “Kyrie fons bonitatis” is a favorite track and one I use often for evaluation. The recording was made in a church of Middle Ages vintage in Munich (if I remember the LP liner notes correctly), and it sounds it. A huge acoustic space, plenty of reverb and what the Head-Space gives me here is a slightly smoother top end on the male voices which can have a slightly gritty texture in spots at times on varying equipment over the years. The question is, which way is correct?

Purcell: Dido & Aeneas: Davis & ASMF: Philips 422 485-2 (1970) / Remastered 2015 on Pentatone PTC 5186 230: Josephine Veasey’s voice in “when I am laid in earth” just drips of heartbreak and loss. This is followed by “with drooping wings” for acapella chorus, and a great test of intelligibility with voices as it is sung in a round and the individual lines of words can be more difficult to follow than singing in unison. This is followed by the same music but performed by the solo strings of the orchestra. I am not much at all of an opera-phile but this performance gets me every time and the Head-Space does a fantastic job of it.

The following cuts are all off Sheffield discs. All were recorded on a Hollywood soundstage, not in a concert hall. The damping of the stage allows for extremely clean reproduction of the orchestra and all its instruments in a slightly dry, but very detailed acoustic space. I believe all are made with custom built tubed recording equipment, were originally direct to disc cut, and used a single coincident tubed stereo microphones for terrific imaging.

Debussy: Afternoon of a Faun
: Sheffield CD24 (1985): This music is all soft focus, pastel colors and perfumes, a dreamscape. It should sound that way, with no hard edges and the Head-Space captures that gossamer like quality very well. The Formula S&P is a little more analytical in its delivery.

Wagner: Siegfried’s Funeral March: Sheffield CD7/8 (1978) : This is great for Horns and Tympani. The drum strokes at times are extremely low level, a test of low level clarity and when the horns crescendo in the middle of the piece I get a real sense of the wide dynamic range in this piece that the Debussy piece does not have. The horns are some of the most concert hall like in my experience; growly, bite-y, with a correct sounding metallic edge especially at low levels. Another key listening post in this recording is the extremely soft tympani strokes that open and close the piece, just a little more air on the Head-Space.

Prokofiev: Romeo and Juliette (ballet): Act 2 Finale (Mercutio’s Death): Sheffield CD 7/8 (1978): A lively piece full of action (the duel scene), lots of lightning fast string playing and pounding tympani and bass drum close it out. Fine on all 3 amps.

Prokofiev: Romeo and Juliette (ballet): Act 3 Introduction: Sheffield CD 7/8 (1978): Intro to Act III. Over the years the 2 full orchestral crescendos that open the Intro have literally crushed some of the most expensive in-room systems clipping the amps. (Well, at least into the late 90’s when the number of audio only stores became more video oriented and I myself downsized, left my purpose built listening room, sold all my 2 channel equipment and moved, taking a 12 year hiatus from hi-er-fi in my home and I directed my music listening time and money to more live concerts. But then in Jan of 2016 I bought an Oppo 105D BRD player and Senn HD600 for more private listening and that pulled me back into the audio fray, but this time with headphones). Tremendous dynamic range on display here, I guess it’s possible to make HP amps clip. But why? I don’t listen at high levels for the sake of my hearing which inevitably has lost some highs now that I’m in my 7th decade. Again all 3 amps perform well, there is just a slight difference in how it all sounds between the 3.

And now into some more standard fare recordings. I have a number of K2, JBL, and other specialty remastered, repressed CD’s but the majority of my music listening is to not so special but decent recordings, as follows….

Bartok: Music for Strings Percussion & Celeste; 3rd Mvmt “Adagio”: Neville Marriner & ASMF (Rec. 1970) on Decca 448577-2:
This 4 movement work uses mirror imaged string orchestras with percussion instruments (including piano which is used more percussively throughout the entire work as opposed to carrying long melodic lines), no horns, and no woodwinds. Very atmospheric with some stark L/R channel contrasts. I’ve picked out the 3rd movement adagio for listening. Foreboding, atmospheric, spooky even, and this is my favorite movement of this work. This music was used in Stanley Kubrick’s film “The Shining” and has been recycled in variations in a number of other films. The use of wood blocks and tympani glissandos makes for an eeire, chilling effect. Another excellent performance of this is Fritz Reiner & CSO / RCA Living Stereo Hybrid SACD 82876-6 1390-2 (Rec. 1955); The Chicago Symphony’s string section is much larger than the ASMF’s and the recording is a bit more dynamic. But the ASMF’s smaller size allows for greater clarity of texture that I think works best with this music. Both are also (relatively) recent re-masters of good quality. All 3 amps are good on this but with the Head-Space I think I get just a bit more atmospheric presentation with a bit more air.

Respighi: Ancient dances & Airs, Suite #3 for Strings;, “Passacaglia”: Antal Dorati & Philharmonia Hungarica (Rec. 1958) on Mercury Living Presence 434-304-2: This final track of the #3 Suite is a soundstage spectacular; the positioning L to R and front to rear should be impressive, especially with speakers. I used this track often for position my various loudspeakers over the years. Even on headphones the imaging, stage width and depth of soundfield should be apparent. Clear but dry string-tone, probably a result of the recording locales ambience, or lack of. The Head-Space and HSA-1b ameliorate some of the dryness a bit better than the Formula S&P but that amp really outlines the groups and with better depth (because it is not so forward?) of the string groups.

Rafe Vaughn-Williams: Symphony #7 “Antarctica”, 3rd Mvmt “Landscape”, Bernard Haitink & London Philharmonic (Rec. 1985) EMI CDC7 47516-2: This track is a bona-fide bass tester. I’ve always been fascinated with the continent of Antarctica since seeing the movie “Scott of Antarctica” as a kid. V-W composed the film score for this movie in 1947. Shortly thereafter he expanded it into a full symphony of 5 movements descriptive of the key events of Scott’s ill-fated expedition. He opens (and closes) the first and last movement with a wordless soprano singing an eerie siren’s song that was subsequently copied over and over in numerous Sci-Fi movies in the 1950’s and going forward. The 3rd movement’s main theme (The hub of this work) shows up around the 3 minute mark of this 3rd movement, and after some additional development gets repeated again around the 5 minute mark, and after a little more development V-W lets the full orchestra and organ explode that theme at around the 10 minute mark. With subwoofers you should feel the organ vibrating your internal organs, but even on headphones the impact should be notable. All 3 amps manage this well even if a bit differently from one another in very subtle ways.

Rachmaninov (or “off” if you like): Symphonic Dances, 3rd Mvmt Finale “”Lento assai: Allegro Vivace”, Donald Johanos / Dallas Sym. O: (Rec. 1991 - AAD on all tube electronics) Analogue Productions AACD 006, (Timing 13:16). This is one of handful of AAD recordings in my collection. This was recorded in McFarland Auditorium at Southern Methodist University in 1967. Accordingly it has a very distinctive sound signature; very dry, very clean, tight, very dynamic, very close up due to the compact stage and auditorium damping (see photo on back jacket of CD). Exceptional impact and dynamic range. At one time I had the original LP on the Turnabout label. Rachmaninov was in perpetual fascination with the “Dies Irae” (Day of Judgement or Wrath) theme. (You should recognize it when you hear it – also used well in the concluding movement of Berlioz “Symphonie Fantastique” another favorite of mine and so forward looking a composition when you consider Berlioz composed it only 5 years after Beethoven’s death). The Head-Space and HSA-1b adds a little warmth to that dry sound and I like it.

Puccini: Tosca: Philips 412 885-2 (1976) Davis and the R.O.H Covent Garden, end of Act 1 My favorite Puccini opera. Lots of great scenes and tunes and all 3 principals die by the end of the opera, pretty standard procedure for any opera. One of my favorite scenes closes Act 1: Scarpia, (the Sheriff), is hatching a plot to get rid of Cavaradossi (a possible member of the “Resistance”), and rape his (virgin?) girlfriend, Tosca, adding her to his string of female victims. He’s plotting all this while standing at the back of the church interior. Meanwhile, in the back ground, in marches a contingent of Bishops, Priests, Altar Boys, and Chorister’s who begin High Mass with chanting and then singing a “Te Deum”. Outside the church can be heard rifle and cannon fire as the “Resistance” scuffles with the governmental authorities. All this is happening simultaneously. The contrast of the subject matter and the goings on in the front and rear and outside of the church intertwine and it is a treat as it builds to a great climax. It’s just too perfect! The ability to separate all these different aspects is something I rely on for evaluation. The recording puts the various elements at appropriate distances and the Head-Space really keeps it all in great perspective and control. This particular CD may be tough to find.

Schoenberg: “Verklarte Nacht” (Transfigured Night) Opus 4 for string orchestra, Riccardo Chailly & Radio-Symphony Orch. of Berlin, Decca 421-182-2, (Rec. 1987): Ravishing string tone so well recorded and the Head-Space with that subtly tube-ish mid-range scores high marks for me. Two other versions I like would be Yoel Levi with Atlanta S.O. on Telarc CD-80372, and with a brighter overall sound palette but equally compelling performance, von Karajan and the Berlin Philharmonic on DG available in several reissued versions. Three different, but ultimately satisfying sonic presentation’s for me on the Head-Space.

Arrigo Boito: “Prologue” to “Mephistophele”, Robert Shaw & Atlanta S.O. & Chorus with John Cheek (Bass), Telarc CD-80109-2 (Rec. 1979): I remember having the original LP issue. This could be another hard to locate CD. This is one powerful piece of music for full orchestra, bass soloist, full chorus and children’s chorus. This will test the capabilities of your entire set up.

On day 8: I went with my usual selections by Prokofiev (“Alexander Nevsky” and the “5th Symphony” on Telarc) and Stravinsky (“The Firebird Suite” (long version but not the complete ballet) on Sheffield and “The Rite” with Salonen on DG) , Shostakovich (“Symphony #5” with Maazel on Telarc), and Rimsky Korsakov’s “Scheherazade” in Reiner’s classic 1958 RCA performance which does show some age compared to some recent recordings, sonically, but as performance it’s among the best.

On day 9: I didn’t want to focus hard for today’s two 4 hour listening sessions with just the Head-Space. Time to relax. For session 1 some classic rock: CSNY, Led Zeppelin, David Bowie, the Police/Sting, and The Doors. For session 2 all Steely Dan. I almost didn’t want to stop playing tracks on the Head-Space.

There’s a lot more I could have listened to and I neglected my Jazz favorites altogether but with just 9 days I had to focus on my main music listening interests.


Without a doubt these are three of the finest sounding solid state amps I’ve ever heard. I do prefer the Formula S&P and Head-Space with both my planar 1266 and cone drive HD800 over the HSA-1b by a small margin.

As all good amps do, all 3 reveal the good, the bad, and the ugly in a recording. In addition there are a lot of other amplifiers out in the wild I have never or will never experience. Even over 5 decades and dozens and dozens of amps I’ve only sampled a very small number of all the possibilities. And especially with the demise of so most audio only stores it’s difficult in the extreme to get to sample all of the new ones as they appear on the market.

In time we may get a more technically oriented review from someone to illuminate certain aspects of the Head-Spaces build, features, and why it does what it does so well.

So, where does this put me? If I didn’t have, or didn’t plan to own the SR1a, I would choose the Formula S&P and Head-Space. The Formula S&P and Head-Space are both special in my listening experience and they appeal to me exactly because of their differences in sound presentation. I really can’t say I’d pick one over the other so for me it will be one of each and many long months of enjoyment running them side by side.

The Formula S&P is very clean, very transparent, and very quiet, very pure sounding and checks all the sonic boxes for me and from all reports can drive any headphone very well with my favored music and at the volume levels I listen at. Its sound reminds me of every good Class A solid state power amplifier I’ve experienced driving speakers over the many years, and it’s a keeper for me. Would I keep it if I were to sell my 1266 Phi? Yes, I think it is just that good for a solid state HP amp.

The Head-Space is also very clean; transparency is there as well but in a slightly different way compared to the Formula S&P. The presence it give voices and instruments is what sets it apart from the Formula S&P for me. I have spent many hours trying to come up with an appropriate one word description for this quality to no avail. It is dead quiet in low gain mode with my either my 1266 Phi or HD800S. The high gain mode is not necessary with my 1266 Phi and certainly not with the HD800S. I’d be surprised to find out that the Formula S&P delivers more power into these loads than the Head-Space based on my re-balancing of volume levels with certain recordings, but it may also be that high gain setting on the Head-Space may only be needed with a small number of extraordinarily power hungry headphones. But then again, I suspect I listen at lower levels of volume than most. For me, loud live music and loud reproduced music are two different experiences. I have never been able to truly match the peak levels and wide dynamic range I experience in the concert hall at the same levels in a home (or store) system even with a dedicated, treated, listening room for speakers or if using headphones.

The ADF and its implementation and how it does what it does is a mystery to me, maybe more info will be forthcoming down the road.

The Head-Space is something I think I’ve been waiting for since the early 70’s when I was in my mid 20’s and into kit-built amps, pre-amps, and tuners. I started with comparing my tubed Dynaco Stereo 70 to my transistorized Dynaco Stereo 120 and began attending more live concerts for a point of reference. At that time the tube versus solid state sound business got added to my quest for exploring the vast number of classical composer’s music and musical styles within periods. Later on came the analog versus digital stuff and more comparisons. The opportunity to do comparison evaluations is a fun and interesting part of the hobby for me. At least with amps and transducers, maybe DACs as well. The other pieces parts that make up a sound system from the sources and especially the connecting wires are an adventure in self-flagellation for me.

This Head-Space to my ears has some tube-like character to its sound for a solid state HP amp. Is it the same sound as the many all tube amps I own currently or have owned over the years? No! But is it a compelling listening experience and different from my experience with other solid state amps over the years? Yes!

The Head-Space sound, set up as it is, strikes me as existing somewhere in between tube and transistor sound with some of the hallmark qualities of both. It does this better than I’ve heard before in similar attempts and with the hybrids I own and at the same time is not lacking in any area of the listening experience. But it’s up to each listener to make this determination for them self.

And again, I want to emphasize that the sound differences in these three amps is not like chocolate, vanilla or strawberry, these are some very close calls in some cases but that’s the stuff that makes it both challenging and enjoyable for me. Almost as much as comparing different recorded performances of the same composition.

One final thought, when I have a new component installed in the chain and I hear a positive improvement I wonder if it might just be the result of the sonic signature of one piece working hand in glove with that of another in the chain compensating each other’s strengths and mitigating the shortcomings? If one could afford to put together a system consisting of the “best” acknowledged component in each category regardless of price I wonder if it still might not produce the “best” end sound? But that’s another call to be made by each individual. Add personal preferences and I think it would not. But that’s enough thinking already. The Head-Space I listened to is one beautiful sounding amp.

Shipping the Head-Space out after 9 days of use just isn’t enough time as was enjoying it way too much. Also, for me, the true test of a keeper is extended use and comparisons over many months but you only get that with any piece of gear by purchasing it. I miss the Head-Space already now that I’ve been without it for 7 days and I wish I still had it here to sustain my listening addiction. As my little gray cells ponder all of this they are also suggesting that the addition of Susvara to my menagerie of headphones with all 3 of these amps under my roof makes sense and is a sound next step.

Such is the life of an audiophile. All things change with time but there is always something to look forward to.

FLTWS June 20, 2021


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Very nice to see your list of recordings!!!!
Makes reading you review SOO much more interesting than those who line up their favourite compressed EDM stuff when reviewing highend equipment.
Cheers CC
Wow, epic review!
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This has been one of the few reviews that (i) I recognize the author [with apologies to @Mad Lust Envy ] and (ii) read it line-by-line. When I grow up to become a real buoy, perhaps I'll try my hand at a review. Not yet. Not yet. Thank you, @FLTWS
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