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REVIEW: AKG K1000 & Sophia Baby tube amp vs. HD580 & Sugden Headmaster

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Thread Starter 
Now that I have two complete and very different high quality headphone listening systems in my possession, I’ve done a full comparative review that I thought would be of interest to the Head-Fi community. It’s way long-winded, so grab a fresh cup of coffee and pull up a comfy chair.

System #1:
AKG K1000 headphones
DIY custom headphone cable
Sophia Electric EL90A Baby tube power amp
(right in photo)

System #2:
Sennheiser HD580 headphones
Cardas replacement headphone cable
Sugden Headmaster headphone amp
(left in photo)

Since the extremely inefficient K1000 phones require speaker-level output power which the Headmaster cannot produce, and since the Baby tube amp lacks any headphone output jack, I cannot do a direct comparison of the individual components by mixing and matching. Thus, I’m primarily limited to comparing the complete systems, although I will infer in some instances which differences are due to the headphones and which are due to the amps.

I’m posting this write-up in the Amp Forum for a couple of reasons. First, my primary intent was to compare the amps, although given the huge differences between the phones, that proved to be a challenge. Second, most Head-Fiers have probably seen numerous posts on the site regarding the K1000 and HD580 phones, and the Sugden Headmaster amp, but I doubt that many have heard the Sophia tube amp, and possibly no one else has heard the Sophia amp as a headphone amp. Nevertheless, members from the headphone side of the camp will likely be interested in my comparative comments about the phones. Perhaps the moderators will provide a link to this review from the Headphone Forum.

I’ll get to the system listening tests shortly, but first I’ll describe some of the other differences between the systems.

LOOKS (see prior picture)
The Sugden Headmaster has been widely considered one of the best-looking headphone amps on the market. (See the recent thread in the Amp Forum entitled “Best looking Headphone amp?”) The Headmaster’s brushed aluminum exterior positively oozes quality, yet in a subtle way that isn’t the least bit gaudy, except for the ugly graphics painted on the top plate, which I in fact removed from my unit, but that’s another story… And the remote control provided with the Headmaster is a rather cheesy plastic affair. (That is also another story, already detailed in my prior posting entitled “Sugden Remote Rant” in the Amp Forum.)

The Sophia Baby amp, by comparison, is retro-cute, similar to my impression of the new Mini cars. It’s footprint is smaller than that of the Headmaster, which is itself fairly compact. The Baby amp’s powder-coated black sheet metal chassis is pedestrian, but I do like several nice touches, including: oval aluminum plate at the base of the tubes; gold-plated volume knob; and an attractive hardwood trim piece on the front corner. In addition to my own unit, I have seen pictures of three other Sophia Baby amps, each of which had different wood trim pieces in completely different places on the amp. I don’t know if this is the case with every Baby, but it would be quite interesting if every unit were indeed personalized in this manner. The simple toggle switch on the front for power on/off, however, detracts from the appearance package.

Straight out of the box, the AKG K1000s look extremely well-built, in their metal mesh and leather cladding. Yet they are butt-ugly, mostly due to the garish red plastic coating on the top bars. (See the thread entitled “Worst Looking Headphones” in the Headphone Forum.) Whoever designed the K1000s was sorely misguided in their choice of color, or perhaps he was just color blind. So, I did what I do with almost everything; I modified. I attempted to paint over the red plastic with black touch-up paint, but the paint wouldn’t stick to it. So instead, I completely removed the offending red by cutting through the coating with extreme care and an extremely sharp X-Acto knife, then just peeling the pieces off. However, DON”T TRY THIS AT HOME, FOLKS! One slip of the knife could be disastrous. I explicitly disavow any claim of damage that anyone else might inflict upon their K1000s in attempting this alteration. If you try it and ruin your $500+ headphones in the process, remember I warned you not to do it.

This seemingly small color change makes a night-and-day difference in the appearance of the K1000s. Underneath the red of the K1000s is bare steel that actually makes the phones look rather cool in a retro-industrial way which matches nicely with the style of the Sophia amp. This combination would be right at home in Terry Gilliam’s film “Brazil.”

Compared to the K1000s, the Sennheiser HD580 phones look like plastic, which of course they are. It’s not that they look bad, it’s just that next to the modified K1000s, the HD580s are out of their league in appearance.

So, in the looks department, my overall assessment: Sugden wins over Sophia, and modified AKG wins over Sennheiser.

I’ve had the HD580s for over eight years now, and I always thought they were fairly comfortable, except that their fuzzy velour earpads made them rather hot to wear in the summer. So when I tried on the K1000s for the first time, I immediately liked their off-ear design and absence of enclosure for physical reasons besides the sonic reasons that I’ll get to later. The small leather temple pads took a little getting used to, but now that I’ve adapted to them, when I switch back to the HD580s, I feel positively suffocated.

The one comfort downside that I have experienced to the K1000s is a bit freakish. One of my listening chairs is covered with a fabric that makes it particularly prone to static electricity. On several occasions, I have stood up from that chair while wearing the K1000s and had static sparks arc from the metal mesh earpieces of headphones to my ears. When I say that these phones have sparkling qualities, I mean it quite literally.

Another aspect that I’ll mention here, although its not a comfort issue, is that the rectangular shape of the K1000 earpieces and the front channeling of the cables from them make it easy to just set them down in an upright position on any flat surface. By contrast, the oval shape of the Sennheisers has always made it difficult for me to find a convenient place to store them. If you lay them down, they tend to flop and roll a little, and they take up a sizable chunk of desktop space. Over the years I’ve tried all manner of hooks and hanging devices for the HD580s, none of which was entirely satisfactory.

With respect to wearing comfort, the K1000s get the nod.

The Sugden Headmaster doubles as a general purpose preamp in addition to its primary role as a headphone amp, so it has a good array of connections, including three sets of input jacks, one pair of preamp outputs, and one pair of tape outputs. The jacks are all gold plated, and very high quality, although I’m not sure who makes them. The Sophia Baby sports only a single pair of RCA input jacks and four speaker output posts. The RCA jacks are gold plated, but rather wimpy, like those you’d find on a mid-level receiver. (Someday when I’m in the mood to modify, I’ll disassemble the Baby and replace the stock jacks with nice WBTs.) The speaker terminals on the Baby are not deluxe, but they are sturdy, five-way screw posts that function very well for use with bare wires, pin terminations, or banana plugs. (I haven’t tried spades.)

Also, because the headphone connection for the K1000s is effectively on the rear of the Sophia Baby amp, it doesn’t have the chunky Cardas plug sticking three inches straight out the front like the Headmaster has.

Both amps use IEC removable AC power cables.

The power switch for the Headmaster is on its backside, as though it were not intended to be used very often, and this is the case as I normally leave it running 24/7. The power switch on the Sophia Baby is a basic toggle switch up front. Its location is befitting a tube amp, which would normally be turned on only when in use.

The Headmaster has large aluminum volume control and input selector knobs, whereas the Sophia has only a much smaller gold-plated volume knob. I don’t know who makes them, but both volume controls are high-grade non-stepped models, although the turning action of the Sophia knob is definitely smoother. The volume control on the Sophia Baby is only a passive attenuator, and as such, the Baby is really just an adjustable power amp; it cannot output a line level signal to another amp, nor is it technically an integrated amp.

I find the center-located position of the volume knob on the Headmaster to be inconvenient when the Cardas cable is plugged in, since from where I sit it forces me to reach around the protruding cable plug to get to the volume knob. Of course, the Headmaster also has a remote control with volume adjustment buttons, but see my aforementioned thread “Sugden Remote Rant” for my opinions of its usefulness in that regard in my system, although this would not be problematic for someone with a different CD player than mine.

Nevertheless, because of its flexibility and array of inputs and outputs, the winner in this category is Sugden over Sophia.

In general, I prefer the low maintenance of solid state electronics over the inevitable replacement of tubes. The Sugden Headmaster is solid state, operating in Class A mode, meaning that it is conducting full current all the time. For reasons I won’t get into here, Class A tends to produce better sound quality than the Class B or Class AB designs used in most solid state amps. Considering that it’s Class A, the Headmaster runs surprisingly cool. It never even gets the slightest bit warm to the touch, even though it’s running 24/7. Perhaps that’s because the Headmaster is really a preamp, not a power amp, so its power consumption must be fairly low.

By comparison, the Sophia Baby is a 10 watt per channel flame thrower. It is also a Class A design, and within seconds of turning it on, you can warm your hands nicely over its tubes. Further description of the Sophia Baby’s electronics is where things get confusing. The gold plaque on top of my Baby reads “Sophia Electric S.E.T. High End Audio”. And the Sophia Electric web site (www.sophiaelectric.com), lists the name of the product as “S.E.T. Music(TM) Baby Amplifier”. However, the specifications for the product describe it as a “Push-Pull” design. If you know enough about tube amps, you will immediately recognize the inherent problem here: Single-Ended Triode (S.E.T.) and Push-Pull designs are mutually exclusive. That is, a Push-Pull design is by definition double-ended, and therefore is not S.E.T.. (S.E.T. designs are usually considered to produce higher audio quality, but they are limited in power output compared to Push-Pull.)

When I called the Sophia Electric company to asks some questions about the Baby amp, I spoke to Richard, who apparently owns the company. When I asked about the contradiction of S.E.T. vs. Push-Pull, Richard explained that the amp is indeed a Push-Pull design. The plaque on top of my amp was actually designed for their other amps that are S.E.T., he said, and they only used it on the first production run of Baby amps because the company has not yet received production top plaques designed for the Baby. (The Baby amp is a new model.) Regarding the S.E.T. Music name, Richard said that it is a trademark name for Sophia’s line of amps, not a description of the characteristics of a particular model. Needless to say, this is misleading in the case of the Baby.

The Sophia Baby uses a total of six tubes: two input/driver tubes, and four output tubes. (A Push-Pull design requires pairs of output tubes PER CHANNEL.)

The supplied driver tubes are type 5670, NOS (new old stock), made in USA. These are fairly common, and available from a variety of tube merchants.

The output tubes are more confusing. The Baby specification describes them as Russian military type 6P1T, although the actual tubes in my unit are labeled “EL90A”, with two Chinese characters above that. The company where I work employs an engineer from China, so one day I showed him one of the tubes. He said that the Chinese characters mean the name Yar-Ran, presumably the brand name, although he was not familiar with that brand. When I spoke to Richard from Sophia on the phone, I asked about the difference in the supplied tubes vs. the specs, and he said that the two are identical. That is, the EL90A tube is the 6P1T, from the same factory in Russia, just with a different label printed on it.

When I did a search on Google on “6P1T tube”, what I got was nothing, nada, zippo, i.e. zero matches. Likewise for a search on “EL90A tube”. In fact, poking around numerous tube merchant web sites, I could not find a single one other than Sophia Electric that sells tubes under either of these identifiers. For tube aficionados, this does not bode well for readily finding replacement tubes in the future, and it basically rules out tube rolling for sonic adjustment. At this point, you might be tempted to stop reading and scratch the Sophia Baby off your list of amp candidates for K1000s. Don’t. Not yet, at least.

When I spoke to Richard of Sophia, he told me that the company bought a “mountain” of these tubes. And the company sells them at a very reasonable price of $10 each. Therefore, the primary caveat here is that if you buy one of these amps, be sure to stock up on a supply of spare tubes. I bought three complete sets of spares, which cost me under $200, and will probably last me ten years of use. Tubes for many other amplifiers sell for hundreds of dollars apiece, and plenty of audiophiles have thousands of dollars invested in tubes for spares and tube rolling. So if you’re concerned about spending a couple of hundred bucks for a ten year supply of tubes, then tube amps probably aren’t for you to begin with.

Like I said earlier, I generally prefer the low maintenance of solid state. Of course, many audiophiles put up with the hassles of tubes for a reason: because they expect (or actually experience) a certain audio quality that they don’t get from solid state electronics.

Regarding electronic design theory, I’ll call it a draw between the two amps.

Finally, we get to the real test here: sound quality. For the listening comparisons, I mostly ran a Marantz CD17 mkII CD player into a Marantz PM-17SA integrated amp. (The CD player has its output muting transistors removed.) All the interconnects involved were Kimber Hero’s that were well broken in. I used both the Tape and CD-R outputs from the integrated into the two outboard amps. The passive volume attenuator of the Sophia amp enabled its use with the line level Tape out rather than running it off the integrated’s variable Pre-amp output. Thus, I could run the identical signal to both headphone amps simultaneously, and quickly switch back and forth between the two systems just by taking off one pair of phones and putting on the other. (I even checked to see that the integrated’s outputs both sounded the same.)

For the K1000 phones, I replaced the amp end of the two-piece headphone cable with a custom cable that I built myself using Kimber 8TC speaker wire. The cable portion attached to the phones remained stock. In a future posting for the Cables/Tweaks Forum, I will compare the differences between my custom cable piece and the stock K1000 cable. But that’s yet another story…

I’ll start out with some general impressions of the two systems, then I’ll comment on their relative audio merits on specific pieces of music.

The HD580/Sugden combo produces an overall smooth and dark sound, with bass being the predominant tone. The sheer abundance of bass that this system can reproduce is astonishing, with real gut-level feel to it. It’s like a subwoofer for your head. This is not to say that treble is deficient, it’s just that bass is so prominent that treble seems to recede. (Perhaps the HD600s would fare better in this regard, but I don’t have a pair to compare.) Imaging is moderately detailed, if somewhat confined by the circumaural design of the headphones. The Sugden amp never seems strained no matter how high I turn it up. (I believe this to be a common characteristic of Class A designs.) For the most part, almost everything sounds very good when reproduced by this combination, and I don’t recall every hearing a single song that sounded outright bad.

The K1000/Sophia combo sounds dramatically different. The overall sound is bright and airy, with treble predominant. The adjustable angle of the K1000 earpieces allows the listener to trade off imaging for bass reproduction by expanding the imaging area through angling outward, or collapsing the imaging area with a gain of bass by angling more inward. I find myself usually preferring the sound when the earpieces are angled just far enough away to clear my outer ears, which is weighted slightly more in favor of imaging than bass. The bass reproduction of this system is actually incredible, not in quantity, but in quality. The full range of low notes is clearly audible, in a way that sounds convincingly real. It’s just not exaggerated in the slightest. My custom cable for the K1000 noticeably improves the bass response over the stock cable, although when I switch back to the HD580s, that K1000 cable improvement seems slight compared to the huge increase in bass with the Sennheisers. However, the HD580 bass seems bloated and lacking in subtlety compared to the K1000s.

One of the reasons I selected the Sophia amp for use with the K1000s is that the Baby was rumored to have tremendous bass output, which I desired as a way to help compensate for the lightness of bass that reviewers often mention with the wide open K1000s. The specs for the Sophia Baby amp state the bass response as +/-3dB down to 6 Hz, +/-2 dB down to 10 Hz, and 0dB to 12 Hz. I don’t know of any solid state amp at any price that has bass response that good. (While I did not attempt to measure the bass output of the Sophia amp, there is no question that this little amp cranks out the bass, which I’ll get into later.) On the other hand, the Sophia Baby also has outstanding treble response (spec: 0dB to 45KHz and +/-3dB to 80KHz!), which when mated with the treble-prone K1000s occasionally produces harshness of a high order. This is definitely not the liquid sound flow one might expect from a tube amplifier, especially considering how smooth the solid state Sugden sounds. (I believe that the K1000s are the primary culprit, which I will also get into later.) Again, my custom cable for the K1000s helps tame the sound to a degree, but not totally. Eventually I plan to experiment with interconnect cables as well.

Even though the K1000 phones only sit about an inch away from my ears, the apparent expansion in the size of the sound field is much greater than that increase in distance would suggest, and thus the music doesn’t feel confined to inside the head. This is not to say that the experience is like listening to loudspeakers, which are clearly “out there” as opposed to “in here”. Rather, it’s as though “in here” is much bigger than with other headphones. And the imaging takes on a third dimension, such that certain sounds or instruments are clearly perceived as being behind or in front of the center plane. The sonic imaging of the K1000/Sophia combination is so detailed and precise that sometimes I am just dumbfounded. The Sophia amp is also dead silent on its own. Even with the volume turned up to the maximum (with no source input), there is no hum or noise whatsoever, which in itself is quite a feat for any tube amp. This creates a blackness of background that further enhances the imaging of the system. Instruments and notes just appear out of nowhere into a precise location in or around the head, then vanish back into nothingness.

When listening to the K1000/Sophia combo, I get the sense that I am peering through a crystal clear sonic window into the soul of the recording. That, however, does not necessarily imply that I am peering into the soul of the music. And therein lies the rub with this system. The K1000/Sophia combo does not artificially dress up the sound one iota, it just exposes the naked truth of what’s on the recording. This level of exposure is of course both a blessing and a curse. On recordings that are truly audiophile-grade in their sonic purity, audio nirvana is indeed achieved. But on those recordings of less stellar sound quality, the flaws are not only audible, they are conspicuous. One can actually hear subtle distortions contributed by microphones or cables, for example, not to mention more obvious flaws such as tape hiss, or hum from an electric guitar amplifier, or the shortcomings of your own CD player.

With all that as a preface, let’s compare how the two systems handle some specific music tracks.

Listening Source CDs:
Steely Dan – Two Against Nature
Rolling Stones – Hot Rocks 1964-1971
Patricia Barber Quintet – Companion
Miles Davis – Bitches Brew

I also tested both amps with FM radio as a source via a Marantz ST-17 tuner.

Steely Dan – Two Against Nature
Whether or not you like these guys’ music, from a sound quality standpoint, this has got to be one of the finest rock and roll studio recordings ever made (except for the first track, “Gaslighting Abbie”, which is noticeably distorted for some inexplicable reason). So I’ll just skip to Track 2, “What A Shame About Me.” Listening with the K1000/Sophia combo, the percussion chimes at the opening positively shimmer, and the bass line throughout is full and deep. Donald Fagen’s vocals come across as extremely natural, although somewhat lean. And the background horn section sounds like real brass without brashness. The muted trumpet toward the end is clear despite being subdued in the mix. With the HD580/Sugden rig, the bass instantly appears as the power of the rhythm. It’s punchy, clean, and stronger than headphones have a right to produce. The percussion and cymbals recede in the mix, but the guitar parts emerge more. The vocals and horns are smooth, but slightly lacking in edge. The vocals actually sound “better” than with the K1000/Sophia, but they are probably less faithful to the artist’s actual singing. With the K1000s, you can almost hear the raspiness of Fagan’s individual vocal cords. Similar impressions hold for most of the other songs.

On “Jack of Speed”, with K1000/Sophia the snare drum beat is so sharp and dynamic, you’d think it’s quicker than the real thing. And on “Cousin Dupree”, the dual rhythm guitars open the tune with plucking riffs that float further out in space than the location of the earpieces, as do the cymbal smashes in the right channel. The backing and overdub vocals on this one come and go from multiple distinct locations in headspace. With HD580/Sugden, the snare softens considerably on “Jack”, and on “Cousin”, the backing vocals are less distinct from each other and the lead.

For this album as a whole, I give the advantage to HD580/Sugden on the vocals and bass, and to K1000/Sophia on everything else. Overall, slight advantage to K1000/Sophia.

Rolling Stones – Hot Rocks 1964-1971
For a second rock and roll album to compare, I deliberately chose one that was of older vintage, and thus not a pristine audiophile original by current standards. Disc One of Hot Rocks fills the bill perfectly here. While the master tapes might have been old and crusty, the transfer to digital for this two disc set was beautifully executed. (This is actually a new dual layer CD/SACD hybrid pressing, but my CD player is not an SACD model.)

Starting with the HD580/Sugden this time, on “Time Is On My Side”, the left channel guitar is obviously distorted and crackly, presumably due to the age of the master tape. The vocals are less prominent in the mix than I would like, but you can still hear the Stones’ less-than-perfect harmonies quite well. The organ part holds up OK, but the drums sound tinny over in the right channel. Overall, the rendering is somewhat muffled. With the K1000/Sophia, tape hiss that wasn’t even apparent with the other system now becomes crystal clear. The instruments and vocals all open up as well, exposing the flaws in the master tapes, and things cross the border into harshland in spots. The tambourine is just plain too loud in the mix.

“(I Can’t Get No) Satisfaction” is where the bass wakes up. With K1000/Sophia, the bass is not particularly deep, but it is loud, as though the recording engineer turned up a bass tone control knob. The vocals are distant, like the gang is literally standing back from the microphone. Switching over to HD580/Sugden, “Satisfaction” sounds like I put on ear muffs. The bass still pushes through, but the Mick and crew just stepped even further away from the mic.

“Rudy Tuesday” brings the lead vocal back to the forefront. With HD580/Sugden, the cello in the left channel is clear and deep, but the drums off in the same channel are heavily distorted. Despite the overall muffling, I can still hear whispered counting of “…two, three, four” during a rest just before the end of the song. With K1000/Sophia, the stereo separation spreads much wider, vocals emerge further from the mix, and the cello takes on the true character of vibrating strings that was hidden with the other head-fi system. And I can now tell that it’s drummer Charlie Watts doing the counting.

Overall, K1000/Sophia takes this album, if you can stand the tape hiss and the raw stridency of the Old Masters on the old masters. However, I can easily understand how some folks might prefer the mellower sound of HD580/Sugden here.

Patricia Barber Quintet – Companion
This jazz recording by Barber (vocals, piano, Hammond B-3 organ) and friends is not only musically outstanding, it is one of the most sonically incredible recordings that I have ever heard, made all the more incredible by the fact that it’s a live nightclub performance. Most live recordings suffer from all manner of foibles, including questionable mic placement, stage amplifier hum or buzz, speaker distortion due to excessive volume, bad room acoustics, random audience noise at inappropriate times, and worst of all, low grade recording equipment tacked onto the soundboard as an afterthought. Not this one; it is nearly flawless. Stereophile magazine has included it among its list of “Records To Die For.”

The set opens with an unconventional take on Sonny Bono’s “The Beat Goes On.” With the HD580/Sugden, Michael Arnopol’s acoustic bass groove is so deep and loud that I have to wonder how it was possible to record it, much less reproduce it through headphones. Barber’s husky vocals flow like an unwinding reel of silk. And in her B-3 solo, I can easily detect the tremolo of the organ’s rotating speaker system. Switching over to K1000/Sophia, the bass isn’t so powerful, but the whole recording takes on an added dimension of presence, in which the contribution of the room acoustics emerge. On the B-3 solo, for example, I can hear how the rotation of the speaker actually sprays the sound around the room and bounces it off the walls. And Barber’s vocals come more forward in the mix, with the articulation of each word revealing how the movements of her lips shape the sound. It’s a startling in-your-face voice, in your head.

Barber’s rendition of Bill Wither’s “Use Me” commences with a great rhythmic solo on bass. With the HD580/Sugden, it sounds wonderful. I sense the sliding of Arnopol’s fingers on the strings and the reverberation of the notes around the instrument’s cavity. With the K1000/Sophia, the bass fingering reveals more of the snap of the strings, and the harmonics of the cavity reverberations seem even more evident. It sounds more “acoustic”. In a few places I can detect a sympathetic vibration that took me a while to figure out its source: the bass notes actually shaking the snares on the bottom of the snare drum. On this tune, the only downside of K1000/Sophia I found was that it also reveals more of the workings of the audience during the bass solo: gentle movement of glasses, chairs, etc. which are quite subdued but nevertheless audible. (I didn’t even notice them with HD580/Sugden.)

Barber’s original instrumental composition, “Like JT”, highlights her piano playing. With HD580/Sugden, the keyboard work is smooth and sweet, with no harshness, but it’s a touch distant, as though the mic is a hair too far away. Likewise for John McLean’s electric guitar solo. But when the whole band gets cooking, the individual instruments start to smear together, losing their individuality among the density of sound. With the K1000/Sophia, the individuality remains completely intact throughout. The piano still seems a little distant, but it sounds more like a stringed instrument than with the other set up.

The disc closes with a percussion-laced take of Peter Green’s classic rocker, “Black Magic Woman.” McClean’s guitar playing is quite good, although not quite up to that of Carlos Santana. But Barber’s slinky and breathy vocals help make this perhaps the definitive version of the tune. With HD580/Sugden, everything sounds well-proportioned. Eric Montzka and Ruben Alvarez’s drum and bongo (or is it conga?) duet adds a smoking finish that comes through loud and clear. No complaints. Yet, when I switch over to K1000/Sophia, this tune becomes totally remarkable. The opening chimes take on a bell-like quality, and I can make out every bead dropping in the rain stick. The guitar takes on a sharper edge, which is definitely appropriate for this song. And most importantly, the entire sound stage comes into sharp focus, with imaging surpassing any I have ever heard in any other audio reproduction system. This dramatic imaging becomes most evident at the very end, when the audience cheers as the stage announcer introduces the band members. What would normally be an undifferentiated mass of applause and yelling becomes a discrete choir of a hundred or so individual folks, each clapping, shouting, howling, and whistling in a distinct position in three dimensional space. This is the stuff that audiophiles drool over. Whatever weaknesses the K1000/Sophia system might have, after listening to Barber’s version of “Black Magic Woman”, it will be hard to go back to a conventional headphone system.

As you can probably guess, I give K1000/Sophia the nod over HD580/Sugden on this disc. But life, and my CD collection, are not filled solely with genuine audiophile quality stuff. So, I loaded up some vintage jazz.

Miles Davis – Bitches Brew
Recorded in 1969 and 1970, originally released as a two-LP set, re-released by Columbia in 1999 as a two-CD package, “Bitches Brew” was the electric re-birth of Miles Davis. It contains a dense mix, with trumpet, sax, clarinet, two drum sets, multiple electric pianos, two basses, plus an assortment of percussion. For this comparison, I used a single long track from Disc Two.

With K1000/Sophia, on the 17 minute leadoff track, “Spanish Key”, the tape hiss is apparent in the quieter passages, although it’s a bit lower pitched than typical for such hiss. Davis’s trumpet is naturally subdued by his delicate playing style, which prevents the harshness or clipping that a blaring horn might otherwise tend to induce, particularly with this headphone set up. Yet the trumpet remains transparent enough to practically hear Davis’s spit. Similarly, Wayne Shorter’s soprano sax is soothingly pleasant, almost like a woodwind (not to be confused with the bass clarinet that is indeed lurking in and out of the tune). And John McLaughlin’s rhythm guitar chops are twangy and light. The left and right channel electric pianos are both fairly distorted. The bass recedes too far in the mix for my taste. Both drum sets are also receded, with only the cymbals prominent, but they are completely separated from each other in the channel extremes. And even with all the resolving power of the K1000/Sophia combo, I still can’t quite make out the few words softly spoken at the very end of the tune, as they blend into the hiss.

Switching to HD580/Sugden, on “Spanish Key”, it was no surprise to me that the bass would come forward. But what did come as a bit of a surprise was how the rest of the instrumentation mellows out into a cool liquid flow, perfectly suited to the music. The trumpet loses some sharpness, but gains in emotiveness. The rhythm guitar softens toward a fuzzy golden tone (like it’s tube amped!) Even the distortions of the electric pianos sounds like they were deliberately induced to emulate a watery feel. (I still can’t make out the words at the end.)

On “Spanish Key”, and on “Bitches Brew” as a whole, it’s as though the sonic shortcomings of the vintage recording are nicely counterbalanced by the tonal characteristics of the HD580/Sugden system, as opposed to the K1000/Sophia system which highlights the shortcomings.

Nevertheless, for CD playback in general, my preference goes to K1000/Sophia for most discs.

In addition to numerous CDs, and the specific CD track comparisons previously described, over the course of several weeks, I listened to many hours of FM radio through both headphone systems. Here in the Boston area, we are blessed with not only a wide range of commercial FM stations, but also two National Public Radio stations (one featuring jazz every evening), and numerous college stations over on the left end of the dial. These college broadcasts include programs for everything from classical to bluegrass to reggae to blues to jazz to world music from countries that I didn’t even know had their own musical styles. It’s a veritable feast for the ears, so much so that I acquired a special FM antenna lengthened to optimize for the so-called “college band” of lower frequency stations.

During the listening phase for this review, I managed to catch two “live-in-the-studio” FM music broadcasts. Such broadcasts are notable in that no recording medium is in the signal path; it’s pure live analog all the way from the studio microphones to the listener headphones. One of these live sessions was a sax-led jazz quartet, and the other was an a cappella vocal group.

With HD580/Sugden, all the FM sounds quite pleasant, if a little restrained. Clearly, the FM signal lacks the sheer punch of the wide dynamic range on CD. But with K1000/Sophia, something nearly magical happens, most noticeably on jazz programming. The stupendous brightness of K1000/Sophia meshes with the rolled off high treble of the FM broadcast signal to produce a wonderful match. It’s like a tailor-made filter, easily producing the best sound I’ve achieved from any FM tuner that I’ve owned. It restores my faith that radio can indeed be a bona fide musical medium, not just a means for advertisers to cram messages into our heads between corporate hits. I can only imagine how good the K1000/Sophia set up would sound with a top-notch FM tuner such as one from Fanfare or Magnum Dynalab, or a 1960’s vintage Marantz 10b tube unit.

By now you’ve probably realized that I prefer the K1000/Sophia system over the HD580/Sugden system for most listening. Since the particular headphone and amp combinations are inextricably linked together in the listening tests described above, I decided to takes the tests one step further, by separating the K1000 headphones from the Sophia amp. Even though I don’t have another pair of headphones to drive with the Sophia amp, I do have another amp that I can use to drive the K1000s, and I do have loudspeakers that I can drive with the Sophia amp. Thus, a couple more tests were in order.

I hooked up the K1000s via my homemade cable to the speaker outputs of my Marantz PM-17SA integrated amp (60 watts per channel). For this test, I ran the amp in source direct mode, which bypasses the tone and balance controls. Then I listened to Steely Dan’s “Two Against Nature” and Patricia Barber’s “Companion” CDs. The sound was generally quite good, with the bass, midrange, and treble all present in proportions roughly equal to the Sophia amp. Treble extension to the very top was a hair less, while paradoxically the overall sound was a little more harsh. And imaging of the soundstage was slightly flattened (less three dimensional) in comparison with the Sophia. I’m not talking huge differences here. In fact, if I had never heard the Sophia amp, I might have been quite content with the K1000s through the Marantz amp. But all in all, I clearly prefer the Sophia amp with these phones.

Next, I switched to the Sophia amp driving a pair of 10-year-old Snell E/III loudspeakers. These speakers are mid-size floor standers, with a woofer/midrange cone driver, dome tweeter, a rear bass reflex port, and a rear-firing super-tweeter. When listening to these speakers with the Marantz integrated, they are remarkably good at both bass and treble, although the midrange is slightly recessed. With the Sophia amp driving them, the first thing that becomes apparent is how much bass this 10 watt per channel Baby tube amp can crank out. And not only is the bass plentiful in quantity, its quality is also marvelous. The acoustic bass on Barber’s “Use Me” is so well-rounded and full, it’s analog sounding, as though it were coming off a high end turntable. On the other hand, Barber’s vocals are imaged in a less precise location than with the Marantz amp, and the Sophia’s magnificent ambient detail curiously detracts from the music when it’s projected through loudspeakers into the listening space with its own room acoustics. By contrast, when listening earlier with the K1000 headphones, this secondary room ambience was absent, so I could really get the sense of being immersed in the nightclub where the recording was made. Listening to Steely Dan’s “What A Shame About Me” over the loudspeakers with the Sophia amp, again the bass is stunning; in fact it’s flat out the best bass I’ve heard from these speakers in a decade of listening. But the midrange and treble sound a bit pinched, which is not the case when listening to the K1000s with the Sophia, or to the loudspeakers with the Marantz amp. I can’t explain why this is so; perhaps it’s related to the difference in impedance between the headphones and the speakers. I can now understand why Sophia is actively pitching the Baby amp for use with horn loudspeakers in general, and the ultra-premium Avantgardes in particular. Besides the high efficiency of horn speakers, which enables them to play quite loud from low power tube amps, the horns really project forward the midrange and treble in the music. I haven’t heard the Avantgarde speakers with a Sophia amp (or with any amp for that matter), but if I’m ever in New York City with some time to spare, I plan to check out the new Avantgarde showroom there.

The mix and match summary is that I prefer the Sophia amp with the K1000 headphones, and the Marantz amp with the loudspeakers, which is how I plan to set up the system in this room going forward.

If you’ve made it all the way through this review, thanks for taking the time to read what I had to say. Hopefully, it will be beneficial to a few folks here in their search for ultimate headphone fidelity.

After this exhaustive (and exhausting) comparison of these two fine headphone systems, I have reached a few conclusions. First, neither headphone system is perfect, however, the AKG K1000s with the Sophia Baby tube amp comes frighteningly close. If only it had a little more bass. Second, given the bass performance of the Sophia amp with the loudspeakers, I must conclude that the K1000 headphones, not the amp, are the limitation with respect to bass reproduction. And third, if AKG ever introduces a next generation (K2000?), I’ll be right up front in line to have a listen. Perhaps, for example, AKG could devise a method to partially reflect back the bass portion of the back wave that now escapes from the rear of the drivers. Or perhaps,… oh never mind. I think I’ll just shut up now and listen to some music for a while.
post #2 of 21
Wonderful review.
Long and interesting, thank you !!
Maybe you can consider some tube rollering or interconnect rollering for your K1000 setup. K1000 is able to produce some good lows but need a lot of tuning. I am using TMC yellow lable interconnect in my K1000 setup. It's working very well, the highs are never sharp and got plenty of punch.
Nice review.

post #3 of 21
Nice review, Bostonears. That must have been alot of work, but I'm sure you enjoyed it.
post #4 of 21
Nice review, although i don't see your K-1000's replacing the HP-1000's in brazil
post #5 of 21
Excellent review, Bostonears!!
I had never heard about Sophia before. Thanks for the lesson.
post #6 of 21
Wow! Great review. What I find most interesting is how you raved the Headmaster's bass, at times describing it as big, bold and propulsive. It seems that I always hear the Sugden has somewhat light bass. Hmm, very interesting. Thanks!
post #7 of 21

oh no!!

If only it had a little more bass. Second, given the bass performance of the Sophia amp with the loudspeakers, I must conclude that the K1000 headphones, not the amp, are the limitation with respect to bass reproduction. And third, if AKG ever introduces a next generation (K2000?), I’ll be right up front in line to have a listen. Perhaps, for example, AKG could devise a method to partially reflect back the bass portion of the back wave that now escapes from the rear of the drivers.
The bass on the K1000 i thought was just about perfecct with Krell/NBS paring with AA push-pull amp. A friend who brought over the K1000 mentioned, also that he gets wee bit more reach down there with Accuphase solid state amp he has been using for the pair.

I'd say it'll ruin the lovely balance of K1000 with more bass output in the low bass region. I think this bass agility or cleanliness is one of the good things going for K1000. I think that the designer made a good call there.
post #8 of 21
Out of curiosity what's the price for each system?

post #9 of 21
Was going to be my next question too... yeah, the price, the ultimate moderator. What is that? I'm curious.

I'm wondering how good would be the Sophia Baby/HD600 combo!
post #10 of 21
I've heard a receding bass line in the K-1000 at times, but that was usually an interaction with the amplifier. I've used an Adcom GFA-535 with the K-1000, and had no issues with the bass at all. My preferred amps with the K-1000 have been Fisher 400 receiver, AudioValve RKV, and carlo-modded Melos SHA-1. With any of these amps, the bass on the K-1000 feels just right.

The Sony R10 could take bass lessons from the K-1000
post #11 of 21
Thread Starter 
Originally posted by Sean H
What I find most interesting is how you raved the Headmaster's bass, at times describing it as big, bold and propulsive. It seems that I always hear the Sugden has somewhat light bass. Hmm, very interesting. Thanks!
I'm not sure to what extent the bass was due to the Headmaster as opposed to other components. There could be lots of variables involved, including the source device (CD player), interconnects, and headphone cable. The Cardas cable definitely improved the bass of my HD580s.

Even my choice of test CDs might be relevant. The Steely Dan and Patricia Barber discs have huge amounts of very clean bass. The HD580/Sugden system doesn't create bass where none exists, but where it does exist, it's reproduced without restraint.
post #12 of 21
Very good review!! Two beautiful systems!!
post #13 of 21
Thread Starter 

Re: oh no!!

Originally posted by kuma
I'd say it'll ruin the lovely balance of K1000 with more bass output in the low bass region. I think this bass agility or cleanliness is one of the good things going for K1000. I think that the designer made a good call there.
Don't get me wrong, I love the articulate sound of the K1000 bass, I only wish there was a little more of it. Perhaps the K1000 bass seems light to me because I've been used to hearing the heavy bass of HD580/Headmaster set up.
post #14 of 21
Thread Starter 
Originally posted by braillediver
Out of curiosity what's the price for each system?
Here are some rough prices at the going rates (of course your mileage may vary):

System #1
AKG K1000 - $550
Upgrade K1000 cable - $190 (That's using the 5 ft. Stefan Arts model as a price reference. My DIY cable actually cost me about the same, but it's a much longer cable, and another long story.)
Sophia Electric Baby amp - $800
Total = $1540 (plus, you would need to factor in the cost of replacement tubes over time)

System #2
HD580 - $200 (Prices vary a lot on these. I paid $320 back in 1995. Now I've seen them under $150 on occasion.)
Cardas Cable - $185 (I got the 15 ft. version)
Sugden Headmaster - $950
Total = $1335
If I were buying this system today, I'd probably get the HD600s, which would add about another $100.
post #15 of 21
Thread Starter 
Originally posted by SuperMario
I'm wondering how good would be the Sophia Baby/HD600 combo!
That would be tricky to do, because the Sophia amp does not have a headphone jack. Anybody here on Head-Fi devised a means to drive headphones off of high power speaker outputs?
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