[ken6217]

Why can’t he post his opinion? Are only glowing fanboy posts allowed?

Comments by the owners of equipment help out potential customers by giving them an idea how equipment sounds. It is more honest than reading reviews from publications that accept advertising dollars.

Btw, with regard to the clicks, that is normal with this upgraded volume control. You hear the same thing on the V281.

 

[Mediahound]

Btw, with regard to the clicks, that is normal with this upgraded volume control. You hear the same thing on the V281.

Yeah, that's considered a volume pot upgrade and is supposed to slightly better. I personally don't like the feel either (had that on my Burson Conductor).

 

[JeffMann]

received my nimbus us4+ last week. Overall, the unit sounds good. however, my experience with the unit has not been entirely positive. The sound is largely neutral. I always felt my ears were sensitive to differences in equipment, but I have to call it like i hear it. In a blind test, there is no way I could tell the difference between this amp and the Headamp GS-X MK2. They sound virtually identical to me, regardless of headphone. I tried many headphones. If I had to pinpoint a difference I might believe the US4+ has slightly more deep bass and maybe the GS-X has very slightly more midrange ...but I really think the difference is so subtle that I'm not entirely sure the difference isn't due to slight variation in volume or my imagination. like I said, in general I hear absolutely no difference in tonal balance, clarity, soundstaging, imaging ,bass tightness, treble sparkle, timber, or any other aspect ...well, except for one pertaining to volume control. I'll get back to that in a moment. I guess it shouldn't be entirely surprising that the GS-X MK2 and the US4+ sound similar to me. They are both excellent, powerful, and in my opinion, try to present a neutral and transparent sound. Here's the thing. The GS-X MK2 is considerably cheaper. So I find my self debating ...is the US4+ worth keeping? For my purposes the answer may be yes. I wanted something that would perform in an alternate location with the performance of my main rig. I wanted something that would maximize the potential of my headphones, including the headphones that are hard to drive. I also like the one-box solution. This makes it easier to setup quickly. I also think the US4+ sounds good shortly after powering up. It may improve in the first 30 minutes or so, but by in large, I do not hear any short comings when starting cold. The US4+ also offers two features my other high-power high-end amps do not. I appreciate the balance control and the remote (which has not yet shipped). The balance control is helpful when the music is imbalanced or when a headphone may have a very slight imbalance. Incidentally, the balance control is somewhat subtle. It doesn't push sound all to one ear or the other, but it is effective enough to compensate for imbalances. The other feature I like is the remote. The remote would be useful if I am listening in my recliner and I do not want t reach too far every time I need to adjust the volume.

But here is my biggest issue - the volume control. The relays click at certain points. I do not think the volume control should be making noises on a 5K+ amp, but I can live with it as long as I know the unit is not broken and as long as it only happens at two spots when turning the volume control. With factory settings it happens at 9 o'clock and around 11:30 on the dial. It's not loud and it's brief. Except the other day I was listening and the click started to happen continuously without me adjusting the volume. To stop it, I simply moved the volume control a little. And then a day later I had a different experience. I heard the clicking more prominently (sounds like static) throughout the entire spectrum while turning the knob. I had been listening to the Susvara and had high gain on the prior day, But today I began listening to the Quad headphones with the same gain setting and (using a line-out on the Meridian Explorer 2 DAC). Anyway, the point is that the volume control is problematic. In addition, I had another issue which admittedly, I could not repeat but it is serious. I was listening with one headphone, pulled it, lowered the volume all the way, inserted a new headphone and the volume was playing as though I hadn't lowered it even though the knob was all the way down. As soon as I touched the knob, the volume reduced appropriately, This could have blown my ears or my headphones in the wrong circumstance. For now, I consider this an anomaly as I did not reproduce this, In fairness, I also did not turn the phone output off when swapping headphones ...not sure if that would have changed anything.

To conclude, I'll point out that I only have a few days with the Nimbus and it is an outstanding unit. It's certainly as good as any headphone amp I have heard. I question the value, but I do not doubt the sound quality. It delivers. It does not standout from some of my other high-end amps, even some considerably cheaper, but as I said, I am not sure it should. As long as the unit strives for neutrality, has sufficient power, is of good quality, and is a good electrical match, most units should sound similar, let's say +/-5 % - just my opinion. I realize others may disagree, The only amp I ever heard that sounded remarkably different (in a good way) from other amps was the Apex Teton ....but that's a different story for a different thread.

From a sound reproduction perspective, I seem to have a much more positive response with respect to the US4+ in my headphone based audio system (PS Audio PWT CD-transport => W-4-S 2v2SE 10th anniversary limited edition DAC => Niimbus US4+ => Susvara) than you and I much prefer it to my V281 which I have owned for 4 years.

However, we seem to have the same "extraneous noise" problem, which you described as follows -: "Except the other day I was listening and the click started to happen continuously without me adjusting the volume. To stop it, I simply moved the volume control a little. And then a day later I had a different experience. I heard the clicking more prominently (sounds like static) throughout the entire spectrum while turning the knob." That description of a static-like noise that can be induced, or affected, by turning the volume control knob is seemingly similar to the problem that I described as a "crackling static-like sound". I think that it signifies that there is a design flaw in the US4+. Although it is not a major problem because the extraneous "noise" is short-lived, it should not be happening in an ultra-expensive headphone amplifier like the US4+. Despite this "extraneous noise" problem, I am going to keep my US4+ because I am so enamored of its sound reproduction quality (which I will describe in a future post).

Jeff.

 

[lithiumnk]

Hello John @project86
I see in your review you have used Metrum Acoustics Pavane Level III R2R NOS DAC with Niimbus Amps. I have recently bought pavane L3 & I already have v281. There is no doubt about v281's performance, its top class. I am thinking pavane deserves an amp like Niimbus (SS) or EC/Auris Audio tube amps. Can you describe the sound with pavane & Niimbus and which HPs benefits the most from this combination?
Thanks

@fdg Any details on availability in Asia ? I had purchased v281 from Munkongadget (Thailand). Thanks

 

[JeffMann]

I am presumably one of the early buyers of a US4+ headphone amplifier, and I have used it for a few weeks now.

Here are my preliminary impressions of its sound reproduction quality. I am not a professional reviewer (like John Grandberg) so you should realistically accord my subjective opinions less respect, but hopefully they can add some subjective impressions to the growing collection of user-based experiences (who are now using the US4+ in the wild).

I am really a musicophile, who listens to music (classical music and opera) for 2-4 hours every day, and I am not really an audiophile who owns multiples headphones and I use only one headphone-based system for my music listening sessions. At this time of writing, my headphone-based audio system consists of the following components-: PS Audio PWT CD-player => Wyred-4-sound 2v2SE 10th Anniversary Limited Edition DAC => Niimbus US4+ => Susvara headphone. The US4+ replaced my V281 which I have used for the past 4+ years.

I am a big fan of Vioelectric headphone amplifiers, and I first owned a V200 model. At that time of purchase, I used a HD800 headphone and I empirically purchased a V200 based on John Grandberg's positive review and because of its reputation for being "warm sounding", which I hoped would tame the HD800's excessive treble energy. It was only partly effective and I was always plagued by the HD800's overly bright, and unnaturally treble-rich, sound. I eventually replaced my V200 with a V281 soon after they came out and I was particularly enamored of its soundstaging prowess when used in balanced mode. I still thought that it had the same "house sound" as the V200 and it could also not completely tame the HD800's overly bright treble sound. I eventually replaced my HD800 with a HIFiMan HE1000v1 headphone, which had a much tamer treble response and it was also much more neutral in its overall frequency response. I eventually replaced my HE1000v1 with a Susvara headphone, which is the "best" and most neutral and most "musically accurate" headphone that I have ever owned.

I was happy with the overall "musical accuracy" of my V281-based system at the time the US4+ became commercially available, and I only purchased the US4+ with the hope that it would eke out a slightly more "musically accurate" sound. I was originally sceptical that it would significantly better the sound of my headphone-based audio system, but it has surprised me in the sense that it has provided far more sound reproduction benefits than I expected - based on reading John Grandberg's review. Here are some of the sound reproduction benefits.

From a soundstaging perspective, it has the V281's ability to produce a large 3-D soundstage where musical instruments and voices are precisely located and where there is "air" (black background) between each instrument. However, the US4+ is even more precise in its instrumental image placement and the locus point of the instrument in the 3-D soundstage never wavers.In other words, it is more precisely focused. The sense of "air" (open black background around each instrument) is even more intense and there is significantly less blurring between adjacent musical instruments when listening to a full orchestra. This remarkable soundstaging quality is particularly evident in some of my opera recordings where there are multiple individual singers +/- a chorus singing at the same time. It creates an aura of being at a "live" opera performance - although the soundstage of my headphone-based audio system is obviously only a minature version (micro-version) of a "real life" opera event heard in an opera hall auditorium. The reproduced sound also has much more micro-detail in the sense that each note of a reproduced instrument (eg. piano) is more clearly separated from the next note with less blurring between notes. This micro-detail carries over to a full orchestra when the sound gets much louder (eg, during orchestral climaxes) and there is less congestion, smearing, blurring of the sound - compared to any previous audio system that I have ever owned in my 50-years of being an audiophilic type of musicophile.

From a frequency response perspective, the US4+ sounds more "neutral" and it does not have a tinge of the slightly warm "Violectric house sound" that characterised my V200 and V281 headphone amplifiers. It simply sounds "neutral" - rather than having a characteristically distinguishing sound that is either too "warm" or too "cold and clinical". I am particularly happy with its treble range, which is more neutral and subdued and far less likely to exaggerate sibilance in soprano voices that can make female soprano voices sound too harsh, shrill or unnaturally bright. Violins, whether in an orchestral string section or in a string quartet setting, sound more musically accurate and less electronically-bright (less metallic sounding). Musical instruments like cymbals, triangles, bells, gongs, plucked guitar/harp strings sound more musically accurate and they are not soft-sounding or unnaturally too-shimmering. I am not a bass-freak and I definitely do not want an exaggerated bass-output when listening to classical music. The bass response of my Susvara (when using the US4+ amplifier) is "tight" and realistically impactful without any woofiness or bass-overhang, and it is marginally better compared to the scenario where my V281 drives my Susvara.

I can sense that the US4+ has a lower noise floor and I can more clearly hear musical instruments when the sound level is very low (whisper soft - pianissimo-quiet), and I presume that it is due to the US4+'s greater dynamic range. That's a great advantage from my perspective because classical music naturally has large varations in sound level (volume level) and it is nice when I can hear the soft micro-details with greater resolution and accuracy. The US4+ also has "tight" control over my low-sensitivity Susvara headphones throughout the dynamic range - even when the sound volume level gets very high during orchestral climaxes. Throughout the dynamic range, the reproduced sound is particularly fluid and grain-free, but simultaneously solid-sounding.

I personally think that the US4+ is a very worthwhile upgrade for a person who can easily afford to purchase one. However, for those V281 owners who cannot easily afford to purchase a US4+, one can only hope that the next iteration of the V281 can offer some of these sound reproduction benefits.

Jeff.

 

[lithiumnk]

I am presumably one of the early buyers of a US4+ headphone amplifier, and I have used it for a few weeks now.

Here are my preliminary impressions of it sound reproduction quality. I am not a professional reviewer (like John Grandberg) so you should realistically accord my subjective opinions less respect, but hopefully they can add some subjective impressions to the growing collection of user-based experiences (who are now using the US4+ in the wild).

I am really a musicophile, who listens to music (classical music and opera) for 2-4 hours every day, and I am not really an audiophile who own multiples headphones and I use only one headphone-based system for my music listening sessions. At this time of writing, my headphone-based audio system consists of the following components-: PS Audio PWT CD-player => Wyred-4-sound 2v2SE 10th Anniversary Limited Edition DAC => Niimbus US4+ => Susvara headphone. The US4+ replaced my V281 which I have used for the past 4+ years.

I am a big fan of Vioelectric headphone amplifiers, and I first owned a V200 model. At that time of purchase, I used a HD800 headphone and I empirically purchased a V200 based on John Grandberg's positive review and because of its reputation for being "warm sounding", which I hoped would tame the HD800's excessive treble energy. It was only partly effective and I was always plagued by the HD800's overly bright, and unaturally treble-rich, sound. I eventually replaced my V200 with a V281 soon after they came out and I was particularly enamored of its sound-staging prowess when used in balanced mode. I still thought that it has the same "house sound" as the V200 and it could also not completely tame the HD800's overly bright treble sound. I eventually replaced my HD800 with a HIFiMan HE1000v1 headphone, which had a much tamer treble response and it was also much more neutral in its overall frequency response. I eventually replaced my HE1000v1 with a Susvara headphone, which is the "best" and most neutral and most "musically accurate" headphone that I have ever owned.

I was happy with the overall "musical accuracy" of my V281-based system at the time the US4+ became commercially available, and I only purchased the US4+ with the hope that it would eke out a slightly more "musically accurate" sound. I was origianlly sceptical that it would significantly better the sound of my headphone-based audio system, but it has surprised me in the sense that it has provided far more sound reproduction benefits than I expected - based on reading John Grandberg's review. Here are some of the sound reproduction benefits.

From a soundstaging perspective, it has the V281's ability to produce a large 3-D soundstage where muscal instruments and voices are precisely located and where there is "air" (black background) between each instrument. However, the US4+ is even more precise in its instrumental image placement and the locus point of the instrument in the 3-D soundstage never wavers.In other words, it is more precisely focused. The sense of "air" (open black background around each instrument) is even more intense and there is significantly less blurring between adjacent musical instruments when listening to a full orchestra. This remarkable soundstaging quality is particularly evident in some of my opera recordings where there are multiple individual singers +/- a chorus singing at the same time. It creates an aura of being at a "live" opera performance - although the sounstage of my headphone-based audio system is obviously only a minature version (micro-version) of a "real life" opera event heard in an opera hall auditorium. The reproduced sound also has much more micro-detail in the sense that each note of a reproduced instrument (eg. piano) is more clearly separated from the next note with less blurring between notes. This micro-detail carries over to a full orchestra when the sound gets much louder (eg, during orchestral climaxes) and there is less congestion, smearing, blurring of the sound - compared to any previous audio system that I have ever owned in my 50-years of being an audiophilic type of musicophile.

From a frequency response perspective, the US4+ sounds more "neutral" and it does not have a tinge of the slightly warm "Violectric house sound" that characterised my V200 and V281 headphone amplifiers. It simply sounds "neutral" - rather than having a characteristically distinguishing sound that is either too "warm" or too "cold and clinical". I am particularly happy with its treble range, which is more neutral and subdued and far less likely to exaggerate sibilance in soprano voices that can make female soprano voices sound too harsh, shrill or unnaturally bright. Violins, whether in an orchestral string section or in a string quartet setting, sound more musically accurate and less electronically-bright (less metallic sounding). Musical instruments like cymbals, triangles, bells, gongs, plucked guitar/harp strings sound more musically accurate and they are not soft-sounding or unaturally too-shimmering. I am not a bass-freak and I definitely do not want an exaggerated bass-output when listening to classical music. The bass response of my Susvara (when using the US4+ amplifier) is "tight" and realistically impactful without any woofiness or bass-overhang, and it is marginally better compared to the scenario where my V281 drives my Susvara.

I can sense that the US4+ has a lower noise floor and I can more clearly hear musical instruments when the sound level is very low (whisper soft - pianissimo-quiet), and I presume that it is due to the US4+'s greater dynamic range. That's a great advantage from my perspective because classical music naturally has large varations in sound level (volume level) and it is nice when I can hear the soft micro-details with greater resolution and accuracy. The US4+ also has "tight" control over my low-sensitivity Susvara headphones throughout the dynamic range - even when the sound volume level gets very high during orchestral climaxes. Throughout the dynamic range, the reproduced sound is particularly fluid and grain-free, but simultaneously solid-sounding.

I personally think that the US4+ is a very worhwhile upgrade for a person who can easily afford to purchase one. However, for those V281 owners who cannot easily afford to purchase a US4+, one can only hope that the next iteration of the V281 can offer some of these sound reproduction benefits.

Jeff.

Thank you @JeffMann for your impressions .
Did you home auditioned benchmark hpa4? The specs especially SNR are unbelievable on hpa4.
Any comparison.

 

[JeffMann]

Thank you @JeffMann for your impressions .
Did you home auditioned benchmark hpa4? The specs especially SNR are unbelievable on hpa4.
Any comparison.

At one time, I was thinking of arranging a home trial audition of the Benchmark HPA4 - but I never did, so I have no personal experience with a HPA4 in my personal audio system.

Jeff.

 

[project86]

Hello John @project86
I see in your review you have used Metrum Acoustics Pavane Level III R2R NOS DAC with Niimbus Amps. I have recently bought pavane L3 & I already have v281. There is no doubt about v281's performance, its top class. I am thinking pavane deserves an amp like Niimbus (SS) or EC/Auris Audio tube amps. Can you describe the sound with pavane & Niimbus and which HPs benefits the most from this combination?
Thanks

Good question. I don't own the Pavane Level III but borrowed it from a friend, and was very impressed. If I didn't already own way too many exceptional DACs, I would likely buy one for myself. It's certainly not cheap, and perhaps the level 1 or 2 versions capture most of the magic for less $$$, but I know I would want to go straight to the top of the line regardless. It's a DAC I could see having a rather long relationship with, just like I have enjoyed with my Resonessence Labs Invicta.

As Jeff mentioned above, the V281 is a great amp. It does so much right and so little wrong that it can be tough to imagine what the Niimbus amp might bring to the table. But with gear like the Pavane, there is more performance to be unlocked, if your amp is up to the task. I think Jeff actually nailed it in terms of the differences when using a DAC of that caliber - soundstage, resolution, neutrality (and not in the negative sense by any means), and a general sense of lifelike realism, are all key factors in the Niimbus experience. Again, V281 is great, US4+ is just better.

As for specific headphones, it's really up to your preferences. The Pavane/Niimbus duo will unleash the full potential of pretty much anything out there, but what it won't do is change the fundamental character. That's a good or bad thing depending on what you want to accomplish. For example a bright Grado will not be "tamed" in the least bit, so I wouldn't go that route if that's what you might be looking for. Same thing with various beyerdynamic models, or an unmodified HD800, etc. The Pavane/Niimbus will show everything the headphone can do, for better or worse.

Personal favorites with that combo include Focal Utopia (extreme resolution), HE1000 mk1 (relaxed yet detailed, superb low end slam, I like the original better than the mk2), Susvara (just amazing all around but very pricey), and Sony's controversial Z1R (not neutral, but enjoyable on the same level as Audio Note speakers can be in the right room/system).

Again I tend to think I'm hearing more of the headphone's character with Niimbus than pretty much any other amp I've tried. I currently have the massive Cayin HA300 tube amp ($4k) running some nice 300B glass, and it does spectacularly well with certain headphones... but seems to impart a bit of euphonic fingerprint in the process. So it's definitely much more dependent upon finding a synergistic partner. Niimbus just plays everything straight and true, whether that's what you wanted or not.

Hope that helps a bit.

 

[Swetone Audio]

I can say that the amplifier circuit does not appear to be exotic, though I have not seen the schematic. Based on the photos, it appears that there are 4 amplifiers, 2 each for the left and right channels, in bridge mode. Each amplifier has an op amp driving 4 output transistors. They have basically added a large current boost to the op amps with the output transistors. The volume control is just a complex relay system. I have not listened to it, but I'm sure it performs well.

 

[TSAVJason]

Merry Christmas Headfiers!

 

[Arniesb]

Merry Christmas Headfiers!

Merry Christmas! Did you heard this Amp Jason whats your opinion?

 

[TSAVJason]

Merry Christmas! Did you heard this Amp Jason whats your opinion?

I have heard it. I’ve been trying to spend at least an hour with every headphone we sell over $1000. This is a marvelous amp! So many ways to use it and ultimately can pair well with the cans I’ve tried with it.

 

[Arniesb]

I have heard it. I’ve been trying to spend at least an hour with every headphone we sell over $1000. This is a marvelous amp! So many ways to use it and ultimately can pair well with the cans I’ve tried with it.

Im gonna have hard time deciding wheter to go for US4 or Headamp GSX Mini or MK2... Head fi is a curse and a bless...

 

[TSAVJason]

Im gonna have hard time deciding wheter to go for US4 or Headamp GSX Mini or MK2... Head fi is a curse and a bless...

Yeah, no doubt! Those are both very fine choices. Tough decision to make. I’d lean to the US4 over the GSX mini. Both both are great in their categories

 

[Arniesb]

Yeah, no doubt! Those are both very fine choices. Tough decision to make. I’d lean to the US4 over the GSX mini. Both both are great in their categories

so i suppose you like GSX MK2 better? Wow you heard mini too nice. What i really like about violectric is reliabilty, great service, Lot of gain settings, balanced from all sources and other good stuff. i bet Headamp amazing too. There is less marketing about american audiophile products, but they all made with passion and love it seems.