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Ultrasone Proline 750 Vs Sennheiser HD600: A Comparative Review

post #1 of 104
Thread Starter 

Good day all. Let me preface this review by letting you all know my reasons for writing it.

First and foremost, there is very little knowledge about Ultrasone headphones out there, despite heroic efforts on the behalf of the "big thread" and the early supporters championing its cause. Particularly amongst the Sydney community very few of us have had the oppertunity to listen to an Ultrasone headphone, and many of us have been very curious about this hitherto-unknown manufacturer.

The HD600, however, is a very well-known and established benchmark in the headphone world, and is still raved about for its musicality, involving warmth, and balance. The purpose of this review is to hopefully give some insight into the strengths and characteristics of the still-much-unknown Ultrasone Proline 750 when compared against the benchmark most of us are familiar with.

The Proline 750 at the time of writing has 150hrs of burn-in, at least 20 of which were spent on my head, accustoming myself to its 'S-Logic' presentation. The HD600 have easily a thousand hours or more. Both are stock cabled.

This review is written using the Pico as a source/amp, with lossless Flac files ripped using EAC secure mode, and ASIO4ALL bypassing windows Kmixer, for as pure a digital signal chain as I can create. While I understand that the Pico, despite being a heavy-hitter for a portable unit is far from a reference-grade home setup, I feel that it powers both these 'phones adequately, and is neutral enough in itself to let me hear the flaws in the 'phones and source material.

A little about me

I have owned the HD600 for about 2 years. Prior to that I owned a Sony SA5000 as my main 'home' headphone. While the Sonys had some fierce advantages over basically any other dynamic headphone out there - excellent speed, unbelievable transient response, microdetail, and clear, crystalline treble - they lacked in some very important areas for me. Namely the domains of tone, body, and bass weight. This made them excellent for some genres, but fairly inept at others.

The Sennheisers in comparison were not as fast, certainly not as detailed, and possessed of mellow, rolled-off treble, made up for all that with inherent, natural musicality, heft, weight, and tonal realism, which ultimately made them better all-rounders for me.

2 years down the track, and I still hadnt found anything I preferred universally over the HD600. Recently a fellow Sydney Head-Fi'er expressed interest in buying my APureSound V3 sennheiser cable, and offered a set of new Proline 750's in exchange. I'd never heard an Ultrasone, so I couldnt very well trade blind, so we agreed to do a temporary swap so that we can both thoroughly audition the respective items at home over the course of a few weeks.

Suffice to say, the trade has since become permanent, with me enjoying the Prolines too much to let them go. Thanks again for cueing me onto these, Ross. You're a gentleman and a scholar

I listen to a very big variety of genres and styles of music. For this review I've attempted to give impressions across as many genres as possible. Anyhaps, on to the review!

Build quality, comfort, practicality

The Proline 750 is not what anyone would call a luxury to wear. The earcups are on the small side, and not very deep, so you're always aware of the contact with your ears. Over time one acclimatizes to this and it becomes less of a bother, but over the first week I was constantly fiddling with the fit and adjusting the earcups to alleviate minor discomforts, which noticably detracted from the enjoyment of the headphone.

The Sennheisers in comparison feel like slipping on a favourite cotton bath robe, they glide into place and around the ears like a comfort. However keep in mind my HD600 has had over 2 years to shape itself to my head, wheras the Prolines have only had 2 weeks. Alot of the comparative comfort I feel could be due to simply being used to the way the Senns feel.

Both headphones feature a removable cable, which I very much like. Ultrasone's implementation goes one step further however, with a single-sided entry and a threaded connector, making it very secure for a removable cable. The stock Ultrasone cable also feels significantly tougher than the thin HD600 cable, sheathed in a thicker layer of insulation.

Isolation and leakage arent really issues for me, however it should be noted that the Proline 750 does leak, and a fair bit at that. Nothing compared to the open HD600 of course, but it is not silent, even with the cups pressed together. Isolation from outside noise is however quite good with the Prolines, completely blocking out the sound of my computer fan, my door opening/closing, the TV out in the lounge room, visitors arriving, and so forth. Good for tuning out.

Some glamour pics of the two heavy hitters:

Enough faffing about, how do they SOUND?

For my comparisons between how these two headphones sound, i've selected 10 reference tracks from different artists and different genres of music, and compared them both using these tracks.

Round one
Diana Krall - The Girl In The Other Room

With the Prolines, this track takes on a lovely sense of intimacy and vibrancy. The mental impression I get is of sitting across the table from Diana, in a softly candlelit venue for two, as she softly croons a private serenade. The double bass and other instruments flank her, slightly behind and to each side, respecting our privacy.

Diana's vocal is smooth and textured, with just a hint of sweetness. It is not a euphonic presentation, and it is not invested with unnatural smoothness nor overt forwardness. It maintains its locality in the soundfield, just across the dinner table from me.

The double bass reverberates impressively throughout this piece, going deep and low and adding a weight and conviction to the whole presentation. Despite the subtle glory of the bass, the Prolines succeed in not over-emphasising it, allowing it to fit naturally into the soundstage in a complimentary rather than overwhelming fashion.

Immediately on switching to the HD600, I notice the vocal has lost some element of intimacy. Diana is no longer sitting just across the table from me. Now it is as if she is on a low platform or stage, with me in a front-row seat below her. The presentation is still close, but its not a private event anymore.

The increased sense of space detracts from rather than benefits this track. Oddly, Diana's vocal seems slightly harsher or more artificial on the HD600 than it did the Prolines. This album is known for bad mastering, so perhaps the HD600 is revealing that more noticably than the Prolines for her vocal.

The double bass becomes bereft of its deep, resonant glory with the Senns, and becomes just another instrument in the background. Cymbal strikes are not as localised, their shimmer is diffused over a wider area, giving them less immediacy.

Winner of round one: Proline 750

Round Two
Dream Theatre - Learning to Live

Very first impression: 'ZOMG the drums!'. Drums hit with a speed and impact that is very noticable, with a visceral feeling that few headphones are able to reproduce. The sound of the drums is possessed of an elastic, organic realism and clear seperation in the soundfield.

The soundstage on this track, however, appears very flat on the PL750. There is width there, but no 3-dimensionality. Vocals are also slightly recessed. The flatness of the presentation detracts significantly from the enjoyment of the track.

With the Senns, the soundstage changes. Localisation and imaging becomes less clear, more diffuse.. but the space the instruments have to work in becomes larger, in both width and height (but still not much depth). Bass is also quite good, not to the level that the Prolines provided, but satisfactory.

Vocals may be a hair less recessed, but still slightly swamped in the soundfield. All in all, the bigger soundstage of the Senns make this track eminently more listenable and engaging than the flat-but-wide presentation of the Prolines.

Winner of round two: HD600

Round three
Enigma - Gravity of Love

The Ultrasone's capacity for deep, textured, 3-dimensional bass is shown exceptionally well here. The subterrainian rumble of the intro on this track is immediately gripping, with the vocals cascading down from above like water trickling through the ceiling of a cavern.

The Prolines imbue this track with a very 3-dimensional sense of space that this track needs. However the clarity of treble on the Prolines also makes some digital artifacts in the mastering of this track more readily apparent. This is forgivable in this instance because the track is very much bass-centric, with treble playing a counterpoint or contrasting role.

Treble harshness/bad mastering artifacts are less apparent on these, noticably so. Bass is shallower, lesseing the effect and believability of the bass echoes and rumble this track possesses.

The 3-dimensional mental image of the soundscape immediately loses some of its definition and conviction. The mind's eye can no longer recreate a scene of standing by a subterrainian lake, as it can with the Prolines.

Winner of round three: Proline 750

Round four
Fleetwood Mac - Crystal

First thing thats noticable here is the unnatural amount of seperation in the soundscape. The lead male vocal is positioned to the very left of the field, with his female counterpoint chiming in on the right. The seperation is pushed to the point that the presentation becomes disjointed and unenjoyable on the Prolines.

Bass lines are possessed of a nice rumble and heft to them, though. I wonder if the unnatural seperation is a product of this era of recording, as I've noticed it with Steppenwolf to a great degree as well.

Male vocal's back closer to the centre, bringing the entire presentation into focus and making the track enjoyable again. The HD600's signature 'creaminess' of presentation also lends itself very well here, creating a soft, sensuous, relaxing experience with this track.

Winner of round four: HD600

Round five
Loreena McKennitt - The Highwayman

Instruments are noticably heavy and resonant in the opening passage. Not a heaviness as in slowness, but heaviness as in very immediate, vibrant, apparent. Loreena's vocals sound amazing through the Prolines. Her voice is gripping, clear, textured, and tonally believable. She is smooth, but not unnaturally so. During some of the more emotional points in the lyric her voice possesses a power to capture and invoke the listener that is portrayed very well through the Prolines.

This track comes off as slightly fatigueing on the Prolines, however, simply due to excessive resonance from the background instruments providing too much detail and musical pressure throughout the track. This does not in any way smear or mar the balance and seperation of the soundstage - there is simply too much going on all the time, and the Prolines seem to refuse to let anything take a background seat, making every instrument readily heard. Which is also not to say that the presentation is overly forward, because it isnt. There's simply an excess of resonance here that one can only listen to comfortably for so long.

Diana's vocal becomes even smoother on the HD600, and somehow ephemeral, as if some sort of seraph or siren were delivering the refrain rather than a human woman. This is a pleasing effect at first, but then one tends to miss the natural believability of the Prolines, which humanise her voice in entirely good ways. Overall the vocal delivery becomes less involving and emotionally gripping on the HD600 because of this.

Background instrument resonance however is tamed, bringing the presentation into greater balance.

Winner of round five: Tied

Round six
Michael Jackson - Black or White

Best way to summarise the effect: I wanted to stop writing and start dancing. And i'm not a dancer.

Very PraTty, full of energy, punchy dynamics, and visceral drum impacts beating out the rhythm. Michael's voice always sounds strained on this track, as if he'd been performing for an hour before singing it, and the Prolines portray this well. Vocals sound primal and tonally believable rather than harsh, creating an overall pleasing effect.

Where did the drums go? Michael's voice becomes harsh and thin. And for some reason or other, the soundstage seems to collapse with the HD600's on this track. What was catchy and involving on the Prolines now sound flat and headphoney. This was the only track where the Prolines demolished the HD600's in every respect.

Winner of round six: Proline 750

Round seven
Nightwish - Leaving You For Me

Intro is immediately gripping. Once the rest of the band joins in though, the poorness of the recording becomes immediately and irrevocably apparent. I suspect this album suffers the effect of the 'loudness wars'. The chorous is completely robbed of enjoyment due to the flat, diffused, complete lack of dynamic range.

However, the Prolines do invest this track with some redeeming graces that make it somewhat listenable. The main bass rhythm of the track is full of heft, weight, and impact, beating out a palpable pulse to the song. Both male and female vocals are also very clear and seperate in the otherwise-uninvolving soundfield.

Intro is no longer immediately gripping. The lack of dynamic range and flatness of the chorous is also less apparent - the bigger soundstage of the HD600 streches the instruments out to increase localisation and imaging. It still doesnt sound very good, but it doesnt sound as bad as before.

This benefit comes with drawbacks, though. Vocals become more diffused, less pure and clear than with the Prolines. And the central bass attack that was beating out the pulse of the music on the Prolines becomes almost unnoticable, bereaving the track of much of its enjoyment. All in all, the Prolines make this track the more listenable of the two.

Winner of round seven: Proline 750

Round eight
Savage Garden - Mine

Holy begeebus. Massively dynamic, clear imaging and localisation, very 3-dimensional soundstage. When the electronic riff starts up in the second half of this track the Prolines create a very eargasmic experience. Combined with the deep drum hits at just the right moments, this was definitely a wow experience with these 'phones.

No contest. Attacks lose their sharpness, dynamics become diffused, as if someone had thrown a blanket over a pair of unruly children. Soundstage becomes flatter, vocal becomes less involving.

Winner of round eight: Proline 750

Round nine
Sting - The Book of my Life

Very textured violins, the attention immediately fastens on them and relaxes at their purity. The light percussion in the intro is amazingly delicate, showcasing a great deal of speed on the behalf of the Prolines. Sting's vocal is smooth, textured and just tonally rich enough to be believable without becoming coloured or euphonic. Seperation and imaging remains very good throughout the track.

Sting's vocal becomes even smoother. Is this a good thing? Perhaps not, as it certainly wasnt harsh or grainy on the Prolines. The HD600 signature creaminess lends itself here as well, coating Sting's vocals like a thin sheet of silk.

While this is pleasing, I'm not altogether convinced that i'd call it better. Sting is naturally smooth and mellow, and this is portrayed in a faithful way with the Prolines. Violins lose some of their texture in favour of heightened smoothness as well, and transient response slows to the point that the delicate percussion that was a delight on the Prolines becomes largely unnoticable.

Winner of round nine: Proline 750

Final round
Tool - The Grudge

Deep bass and visceral heft serve the Proline well here. Transient response again excellent, highlighting the fast percussion of the intro. Very 3-dimensional presentation throughout. The lead singer's voice has a guttural primal nature to it that makes this song so gripping.

Where did the drums go, again? Slower transient response becomes apparent, as the percussion once again blends in and diffuses with the rest of the instruments. Vocals lose some of their primal texture, becoming more generic and smoother.

Winner of the final round: Proline 750


round 1 Diana Krall: PL750
round 2 Dream Theatre: HD600
round 3 Enigma: PL750
round 4 Fleetwood Mac: HD600
round 5 Loreena McKennitt: Tied
round 6 Michael Jackson: PL750
round 7 Nightwish: PL750
round 8 Savage Garden: PL750
round 9 Sting: PL750
round 10 Tool: PL750

2 rounds to the HD600, 7 to the PL750, and one tied.

Would I call the Proline 750 an overall better phone than the HD600 because of these results? Certainly not. They are different, and both excellent in their own ways.

That said, the Ultrasones strike me as the more refined and technically capable of the two, possessing greater finesse and dynamics, whilst maintaining a natural, enjoyable, neutral tone. The Prolines remind me a good deal of my old Sony SA5000, with their most unforgivable flaws remedied. Perhaps not quite as fast or as microdetailed as the Sonys (which I still view as the closest a dynamic 'phone has ever come to electrostatic speed), but possessed of a much fuller, richer sound, deep and heavy-hitting bottom end, and BODY, which the SA5K lacks without top-notch amplification and/or balanced operation.

The Ultrasone gurus tell me that at 150hrs the Prolines should still have a bit of burn in to go, so I look forward to further refinements in their sound as they loosen up and as I accustom myself to them further. I hope this review was informative and shed some light on this stealth-bomber of a headphone.
post #2 of 104
Nice !

I'm suprised that you prefer the HD600 for Dream Theater. You should try again with their more recent albums like Train Of Thought or Six Degrees.
post #3 of 104
Thank you for a great post.

(I also own this pair -- well almost, I have the new Pro 750's [headband and padding upgrade over the ProLine] and the Senn 600's, but both re-cabled. I have compared them to each other, and also to my Beyer 600 Ohm DT880's (not yet, but awaiting, re-cable). I have nothing to add to your fascinating conclusions at this time. You have covered the subject perfectly IMO. Note it is tricky -- as you yourself point out -- comparing closed, open, and semi-open phones ... they have different isolation and leakage goals.)

Again, a great read!
post #4 of 104
Thread Starter 
Originally Posted by wavoman View Post
Thank you for a great post.

(I also own this pair -- well almost, I have the new Pro 750's [headband and padding upgrade over the ProLine] and the Senn 600's, but both re-cabled.
Thanks for the compliment

Now you mention it, mine may be the Pro 750's as well - I wasnt aware there was a difference. The headband reads 'Pro 750', as does the box. I hadnt heard that the Proline had a headband/padding change and a name change to go with it.
post #5 of 104
Hee Finally the review. Very detailed review!

The PROline has some plasticy thingy as the faceplate on the earcups whereas the new PRO series, they switched it to a metallic faceplate. The PRO's as well have a thicker earpad compared to the Prolines according to Ultrasone but it does not sonically sound different than the PROline. And the PRO series gets a hardcase to keep their headphones too.

Now you're making me want a pair of Ultrasones more.
post #6 of 104
Thread Starter 
Originally Posted by ZephyrSapphire View Post
And the PRO series gets a hardcase to keep their headphones too.

Now you're making me want a pair of Ultrasones more.
Yup, definitely got the carry case. And a coiled cable, 6.3mm to 3.5mm gold adapter, instruction book, demo cd, and a set of replacement earpads

I was impressed with the accessories it came with, to say the least. The only things I can think of that it lacked is a short cable for portable use (purchaseable seperately through Ultrasone), and a headphone stand
post #7 of 104
tremendous review. very detailed and informative. btw, i recommend using pink-noise to burn in your headphones instead of the songs you use. trust me, it speeds up the process dramatically. a lot of people find changes occuring in the sound of the prolines for 300 or so hours. i definitely didn't hear anything change after 200 hours (and even that's slightly exaggerating it), since i used pink noise at slightly higher than listening volumes throughout the burn-in period. also if you find the prolines clamp too tight, you can stretch them safely by bending the top white portion of the headband (metal inside). i found it became much more comfortable after a bit of stretching.
post #8 of 104

Reply to Covenant re. review

Originally Posted by Covenant View Post
Thanks for the compliment

Now you mention it, mine may be the Pro 750's as well - I wasnt aware there was a difference. The headband reads 'Pro 750', as does the box. I hadnt heard that the Proline had a headband/padding change and a name change to go with it.
Yes, I own the Proline 750. On the headband, it reads "Proline 750". I thought your review was very well written and informative. Thank you for writing it. There is one thing I would like for you to do and ad to this review if you are able.
Find a professional recording studio. You may be able to do this for free if you can find out when their off times are. Or, they may be interested in knowing about this comparison. In the recording studio, play your music over their monitors. If this is a pro recording studio, chances are very high they will have high quality studio monitors. Listen to your music over the studio monitors than put on the Pro 750's. Do a continuous A/B comparison. I believe you will be amazed at how similar is the sound coming from the Pro 750's when compared to high quality studio monitors.
Of the headphones I've heard, I've never heard a headphone that reproduces the sound of audio from flat response (no additional EQ setting) high quality studio monitors in an acoustically controlled room better than the Proline 750's.
What I think you will find is the few "deficiencies" you heard when listening to the Pro 750's you will also hear very similarly to a great extent when listening to the studio monitors "play" those same tracks. In other words, what I'm saying here is that the Pro 750's were probably representing the sound of the actual recording and your audio chain better than the HD600's. The Pro 750's are very revealing headphones.
One other suggestion, do a comparison with Big Band Jazz. And another with an orchestra with strings.
The Proline 750's reproduce the sound of musical instruments better than any other headphone I've ever heard, IMO. I've done a lot of work with musicians and I've heard them play their instruments "live" many times. Here, I'm referring to not just small groups but also to full orchestras as well. It's phenomenal , IMO, how accurately the Proline 750's reproduce the sound of musical instruments.
Thanks again for writing the great review.
post #9 of 104
Thread Starter 
Originally Posted by Peter Pinna View Post
There is one thing I would like for you to do and ad to this review if you are able.
Find a professional recording studio. I believe you will be amazed at how similar is the sound coming from the Pro 750's when compared to high quality studio monitors.
This wont be happening, my schedule is just too busy for that sort of foray. I had trouble enough finding the time to write this review. I'll take your word for it, though, as they do strike me as a very studio-capable headphone.

One other suggestion, do a comparison with Jazz. And another with an orchestra with strings. The Proline 750's reproduce the sound of musical instruments better than any other headphone I've ever heard, IMO.
One reason I didnt include jazz or instrumental/orchestral material, aside from time constraints and desire to keep the review to a manageable size, is that my intention for this review wasnt just to highlight the Pro 750's strengths. The purpose for the review is to take material that would sound good on both headphones, and find out exactly how they differ.

I could have biased the review towards the Ultrasones quite heavily by using alot of instrumental tracks - its greater speed, imaging abilities and sharpness of attack lends itself very well to instrumental, and i'm sure that they would trump the HD600 on most if not all such material.

Another reason I didnt include such material is that a very important criteria for me in any headphone is the sound of the human voice. Vocals are one of my paramount priorities, and so all of my test tracks had at least some vocal element.

Thanks again for writing the great review.
You're very welcome.
post #10 of 104
Good deal, you DO have the PROs, not the older ProLine. And since they are closed phones, the thicker padding and the re-worked headband in theory can create a different seal, and thus a difference in SQ.

Why buy old stock? Everyone should look for PRO not ProLine on the headband.
post #11 of 104
Originally Posted by wavoman View Post
Good deal, you DO have the PROs, not the older ProLine. And since they are closed phones, the thicker padding and the re-worked headband in theory can create a different seal, and thus a difference in SQ.

Why buy old stock? Everyone should look for PRO not ProLine on the headband.
Err.. because Ultrasone said it was just a makeover and the sound of the PROline and the PRO are no different? But I do prefer the better accessories provided with the PRO series though. Hardcase. Yum
post #12 of 104

Reply to Covenant

I made a mistake in my post. I meant to write a request for you to do a comparison involving BIG BAND Jazz, not just Jazz. Indeed, you did one involving Jazz with Dianna Krahl who is a Jazz singer and her usually small group accompaniment is Jazz influenced. I edited the post so that it now reads as a request for a comparison involving "Big Band" Jazz.
Believe me, I understand the time constraints. I deal with them, myself.
I, too, have a strong appreciation for vocals and that is definitely one of the things that has pleased me the most about the Proline (Pro) 750, the way it "portrays" the sound of the human voice. If you haven't heard Ella Fitzgerald, especially from recordings of the late 1950's and 1960's via the Pro 750's, I strongly suggest you do hear them.
"Rock" music, groups such as The Steve Miller Band, Wilco and Cake are not really my preference. You might think of me as kind of "old school" in my musical tastes, preferring instead the classic singers like Ella and Frank and cooking Jazz Big Bands like Count Basie and Duke Ellington and Classical Music such as Mozart, Brahms, Beethoven and Chopin played by virtuoso performers.
However, a friend of mine supplied me with some recordings of the "Rock" genre (varying types of "Rock" Music) which I used to test, out of personal curiosity, the limits, adaptability and flexibility of the Proline 750's. As far as I can tell, in the "Rock" Music genre, overall, the 750's performed magnificently. Actually, the 750's performed so well and their produced sound of the "Rock" Music was so realistic that after playing the "Rock" Music, they jumped off of my head and attempted to smash themselves several times on the floor as a climax grand finale!
post #13 of 104
Nice. Now just wait till you hear the Edition 9...
post #14 of 104
Thread Starter 
Originally Posted by HeadphoneAddict View Post
Nice. Now just wait till you hear the Edition 9...
Bad Larry.
post #15 of 104
Ive also been interested in ultrasones for a long time. Was there ever a hands down conclusion on the 780 vs pro 750 debate?
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