Posted by Greg B on 1st Nov 2013
I received the the Kratos. OMG, what a difference. I am very happy. An upgrade to the original no doubt. Speaking of that, How much will it cost to buy the original I have?
Posted by John H on 24th Jun 2013
I was lucky enough to listen to both the Kratos and Nuforce's version of the same technology this past week. Nuforce's DDA-100 is the same power output at 100wpc and retails for $549. It has a crystal clear sound, but leaves a little to be desired in terms of tonality and musicality. Then we brought in a brand new Kratos, and Ryan informed me that it sounds pretty bad for the first 300 hours or so... either he's wrong or he's got one hell of a giant killer here. His Kratos outclasses the Nuforce and, quite literally, any digital system I have ever heard to date. It is both noiseless and emotionally involving with proper tonality and spatial accuracy. It is literally so much better than my previous reference it's just hard to compare.
I was using a Lynx Hilo previously powered by one of Core's Kora power supplies, which is a fantastically good DAC. But his Kratos is a different animal. There's virtually no need or conception of something better in my system.
Posted by Unknown on 11th Jun 2013
This is hands down the best sounding amp I've used. I've been interested in getting a power DAC for a while now. Boy am I glad I did! Simply put, I feel like I'm hearing music the way it was intended for the first time. Core Audio is fantastic and I can't wait to expand my current set up.
Posted by Unknown on 11th Jun 2013
This is my first fully digital amplifier. I was not expecting it to sound this good honestly. I figured I would give it a go since Core Audio offers a 30 day trial, but I am definitely going to hold on to this. I could spout off all sorts of technical jargon but the bottom line is this thing just sounds great. I guess maybe the power DAC is the way of the future after all!
Posted by James C. on 29th Mar 2013
About two months ago I did a review of Core Audio Technology's entry-level power supply for the Mac Mini which can now be found on this forum. Since then, I've added their Kratos digital amplifier to my system and feel like I'm ready to give some thoughts.
I said it the first time around and I'll say it again -- I think this company's gear is a game changer. I went to the New York audio show this weekend and came away feeling extremely good about my Core Audio Tech stuff. My most recent setup -- which is about as bare-bones a system as Core Audio Tech offers, and which is already somewhat out of date by the standards of this extremely fast-moving company -- sounded quite excellent versus most of what I heard there -- and probably better than just about any digital configuration I remember hearing there regardless of price. Indeed, I found myself mostly comparing the sound of my system to the high-end vinyl setups. To be fair, there were a few that probably left my setup in the dust in most respects - the Walker Audio room comes to mind - but those setups also tended to have price tags well over $100k.
Core Audio Tech's owner Ryan Mintz tells me I'll experience a pretty dramatic improvement with my next upgrade. That slightly boggles me, but at this point I'm also inclined to believe it. I won't delve into technical details here, as those are pretty well laid out on the site, and Ryan is quite responsive to queries via email. Essentially, the company takes a radical approach to shortening and simplifying the signal path and feeding it with super-high-quality power supplies. Among other things, that means getting rid of as many separate components and cables as possible. It's a philosophy that made sense to me from the get-go, and left me wondering why nobody else seems to be doing it. After listening to this gear, I'm still wondering this. So rather than obsessing about interconnects, power cables, speaker cables, tubes and tweaks, I'm obsessing about upgrading to the next-level power supply, upgrading the external clock and its power supply, upgrading the music server, simplifying the signal path by converting my system to an all-in-one unit, etc. The thing is, unlike with a lot of past tweaks and upgrades, I am pretty confident that each upgrade I make now is going to make a real difference.
As I hinted above, this is digital audio that sounds very un-digital. To me, that's about as great a compliment as I could give it. I've always been a vinyl guy at heart, and when I talk about my vinyl ideal, I'm not talking about warm and fuzzy, I'm talking about the real stuff. I'm talking about vinyl that delivers a huge, lush, energized soundstage, seeming to load the room with torrents of musical information with each passing instant - a presentation that's bold and effortless, stimulating yet relaxing, capable of sounding not merely "life-like," but even "better-than-life-like." Truly, in a good vinyl setup I've always felt that when the needle is descending toward the vinyl groove, my black-and-white world is about to go Technicolor.
So does this entry-level setup - the Kratos digital amp fed by my Mac Mini with the Core Audio Tech power supply - get me there? Well, to an impressive degree - to a greater degree, for sure, than any other digital configuration I've heard that doesn't involve a DAC with a price tag well into the five digits. The key thing for me is that it delivers an analog sound without resorting to "smoothing over the edges," the way most digital equipment that claims to sound like "high-end vinyl" does.
What do you get instead of smoothed-over edges? I think of it as a lush meadow of sound, bristling, chirping and grunting with a plethora of pleasing detail. Yes, it untangles Wagner and Mahler wonderfully. The whole presentation is nicely balanced from top to bottom. There's deep, tight, textured bass. Trebles are extended and refined, yet proportionate and not in your face. On good recordings they can veer towards a kind of silky beauty. A recording of a cheering crowd in a live arena, for example, recently struck me as sounding a bit like waves crashing on the beach. That's the kind of thing I pay for. Hi-hats and cymbals sound like actual brass discs that are vibrating after being struck by wooden sticks, as opposed to the tizzy white-noise-inflected crashes that are typical of lesser digital. Horns bite, but cause pleasure rather than pain when they do. The harmonic richness, the timbral accuracy, and the dynamic finesse, micro and macro, are all wonderful. Charles Mingus' upright bass is an exquisitely crafted box of aged spruce and maple that's getting manhandled, flailing violently to punch its way out of the vise-grip it's in. Sarah Vaughn's voice is uncannily convincing: deft and precise, sensible and sad, spookily hanging between the speakers. Like a small mirror might fog up if you held it there.
So we're obviously a little inspired here. Still, it's not necessarily all things to everybody. The soundstage, while impressively three-dimensional and large, mostly hangs in a space that's even with the speakers. Folks that want a bowling alley to open up behind the wall and spill into the neighbor's yard may need to do some work. And while the Kratos seems to be almost supremely fast and transparent, that might come at the expense of a certain palpability and fleshiness to the presentation that I get with my beloved Sam Kim Heathit EL84 integrated in full triode mode. This comparison also holds somewhat true versus a Red Wine Audio Signature 30.2 LFP-V integrated amplifier I recently took in on trade (a special amp in its own right for sure). It should be said, however, that my speakers, the Tonian TL-D1s, also share that tendency, and I am guessing that many other speakers might deliver significantly more flesh when paired with the Kratos. Lastly, there still are some digital artifacts evident in the presentation on some recordings - the roughed-up Steinway in Glenn Gould's 1982 issue of Bach's Goldberg Variations is still a bit of a challenge - there's a wee bit of midrange glare and fatigue there. A piano, of course, has an enormously complex sound that is probably the most difficult thing for digital to get right in my experience - especially when it's being played hard and closely miked. But I must emphasize that it's an impressively small amount of this trouble on a fairly small minority of recordings. Most Bill Evans recordings, for example, fare far better.
Meanwhile, well-recorded classical and jazz, as well as rock like Fleetwood Mac, Steely Dan, the Eagles, etc. - even if it's redbook and recorded in 1959 - really does come very close to sounding like it's coming from a kick-ass vinyl rig. Thrilling. And again, this is despite - or rather, because of -- the fact that the Core Audio system appears to be doing nothing to cover up or paper over the distortion with something slow, smooth, opaque or otherwise euphonic -- what Ryan likes to call "pleasing distortion" that's getting in the way of the real music. It's also despite the fact that my Tonian speakers are not known to be the most forgiving.
The issues notwithstanding, I'm mostly impressed that the performance is already as good as it is despite being an entry-level setup. For the first time, I feel that I'm not fundamentally disappointed with my digital. I'm getting the musical flow, the "time, tune and tone," the "fun factor" that Ryan likes to go on about if you end up getting into a conversation with him (always interesting and educational, in my experience). Come to think of it, it really is kind of like stepping into a Technicolor Oz, in that I no longer feel susceptible to being bored and "watching the music go by," which was the key complaint I've had for years with most digital.
It should be said that the break-in period for Core Audio Technology gear is, in my experience, lengthy. But it's also not without its rewards. Like the power supply for the Mac Mini, the Kratos amp started off sounding pretty good, but took a week before it started to really impress, and frankly, more than a month before it started to blow my mind. Up until a few days ago, when I traded away my Mini and PS to upgrade to a new Core Audio configuration, the system seemed to be having fresh spurts of improvement each week. Frankly, it strikes me that this puts Ryan in a slightly awkward situation, given that his free trial period is only 30 days. But the stuff does sound plenty good at that point.
So bottom line, unless I hit the lottery and am in a position, for example, to splurge on a Walker Audio Proscenium Black Diamond turntable, I'm pretty sure I'm going to remain relatively undistracted by all the other stuff that's out there. But even if I do hit the lottery, I can't imagine also not simply splurging on upgrades to what I've got now. Above all, I'd encourage folks who are afraid of a digital amp that sounds "digital" to have no fear. I wouldn't say the amp sounds like tubes exactly, but I wouldn't say it sounds unlike tubes either (like flea-watt SETs with more watts, maybe). The thing keeps getting better with break-in, and the more it breaks in, the more it sounds -- a bit of a revelation for me, mind you -- exactly like I want it to sound.
Posted by Jeff W. on 29th Mar 2013
As I wait for the imminent delivery of the "Super Amp" Ryan has created for me I am enjoying a loaner S1 with Kalos power supply more than anything I have heard and way more than my previous electronics. I have quite revealing Adam Tensor speakers with Heil transformer tweeters AND midrange drivers. My digital source is $13K Esoteric UX-1 transport extensively modified by Great Northern Sound, so what goes in between is going to be heard very acutely!
I had been VERY happy with my Concert Fidelity preamp with vintage tubes, Weiss DAC and new generation Mark Levinson Amp- total cost circa $35K. And of course $3K in interconnects and another $6K for AC cables and the required $5K power conditioner to get the best from the lot. So pretty much $50K-yipes!
So, now I want to tell you how much better Ryan's amp sounds and I feel stuck. It's SO much better that comparing and contrasting doesn't come so easily. It's not like comparing spending the night with one Hollywood starlet vs. another. It's more like comparing spending the night with both of them vs. having a bowl of oatmeal.
Adjective roll call-WAY MORE: lifelike, detailed, musical, rich and nuanced, effortless, fun, relaxed,tonally complete, dynamic- An explanation comes to mind (a starlet free explanation)- with any other traditional electronics I have heard- they are for better or worse- working hard to keep up with and convey the music, while this system (not really just an amp in practice) seems to be deciding to play the music on it's own terms at it's own pace( it just happens to be exactly what was recorded!) so there is NO sense of effort and it is NEVER off in any way. Job well done!
PS: any reasonable person who has heard many stereos as I had, will conclude I'm nuts because unil you hear this stuff you simply have NO IDEA.
Posted by Greg B on 29th Mar 2013
I received the amp. It has been a long journey for me, but I was finally able to hook it up and hear music. My expectations went from curious enough to try something new, to frustrated, to really amazed at how good this sounds. I have been an audiophile for a long time and have spent tons of money searching for the ultimate sound. I have owned Krell, Mark Levinson, Parasound JC1 and just about every high end DAC with a good review. However, even before "burn in" this set up sounds better than anything I currently own and anything I use to own. You are really on to something.
Posted by Don W. on 29th Mar 2013
I made an adapter for playing my Audeze LCD-3 headphones through the Kratos. It is simply 4 speaker wires connected on one end to the speaker posts of the Kratos and terminated on the other with a standard 1/4 inch headphone jack.
The result is astounding! The Kratos has become my favorite headphone amp, hands down. I've never felt so much like I was sitting beside the producer in the engineering room while the musician is playing. Every detail, every nuance, comes through without distortion and without glare. If it seems a little bright on some recordings, well, that is because you are sitting in the engineering room! That is the DETAIL of the recording, coming through un molested. And there is plenty of thump and bump (when the music calls for it) without feeling over done in the slightest.
Now I want to share a little tip I recently discovered. My other favorite headphone amp has a built-in cross feed circuit - implemented in the analog domain - which makes music through the headphones more natural, musical and less fatiguing. I LOVE it and while the Kratos sounds amazing I was expecting that I would continue to use my other amp often for its cross-feed. Then I thought about the potential of DSP.
I use JRiver as my music player software and it comes with a built-in cross-feed plug-in. But I have never been very impressed with it. Based on that, I had pretty much discounted DSP based cross-feed. But when I set out to find another implementation it didn't take long to come across ToneBoosters Isone. This is a plug-in for the DSP unit of JRiver (it is based on a standard so it will work with many common music players.) I think it is masterfully made. Its purpose is to simulate through headphones what a listener would hear if he was actually listening to speakers (that is what cross-feed is.) It has options for adjusting the attributes of the room (size, speaker placement, surface, etc.) the frequency response graph of the speakers and the listener's head and ear size, all of which interact in the real-world to affect what one person actually hears. I highly recommend it.
As a general rule, I have found, if I want to experience what it is like to be the music producer or engineer, then I listen without cross-feed. But if I want to be in the audience, to hear the music as it was intended to be heard, then I need cross-feed. I'd say this is true of most, but not all, recordings. (Some recordings just don't need cross-feed to sound natural through headphones. It's either that cross-feed has been added post production, or just the way the music was recorded, or something else. I don't know enough about the business to say.) With the magic of DSP, I can have it both ways in first class audiophile quality with the Kratos.
Incidentally, I mentioned above that some recordings might seem a bit bright, but only because that is how they were recorded, and the Kratos (and the LCD-3 headphones) are simply being true to the recording. Well, with cross-feed applied, 100% of the time (in my experience) the perception of brightness is removed. It makes sense that it would be so because, in a natural environment, where the sound waves are bouncing around in the room, the high frequencies just aren't being directed directly into your ear drums!
The Kratos, unlike conventional amplifiers, handles all signal processing and amplification in the digital domain. It is a fully digital amplification design also known as a 'Direct Digital Amplifier'. The design has no A/D conversion, no analog preamp or separate amplifier. There is no analog in the signal path at all.
The pristine signal from your source is sent via SPDIF into the amplifier. The SPDIF signal is a PCM (Pulse Code Modulation) signal, which is a type of digital signal transmission. This PCM signal is converted to a Pulse Width Modulation, which is another form of square wave containing amplitude and timing information. As a PWM, the signal is reclocked, amplified in the digital domain, reclocked again, and then demodulated to drive a speaker directly. There is virtually no analog in the signal path all the way up to the binding posts.
This technology is different from a Power DAC in so far as a Power DAC has a D/A converter and either class A/B or Class D amplifier in the same chassis. That is not a fully digital amplifier. A Class D amplifier takes an analog input, converts it to a triangle wave and then again into a square wave. In the case of a fully digital amplifier it takes a square wave at the input, converts it to a square wave, and amplifies directly. PCM to PWM conversion is far lower distortion, eliminates extra stages of D/A and A/D conversion, and provides a direct signal path for your system. With precise Jither algorithms we are able to control this PWM information and output a signal with extremely low harmonic distortion. This means you hear more of the real harmonic content and less of the noise and artificial harmonics that plague digital playback systems. It's an extremely musical, organic sound that is non-fatiguing and quite addictive to listen to!
As with all Core Audio Technology designs the spine is in our high bandwidth, ultra low noise linear power supply. The downfall of digital amplification is that they use inexpensive switchmode power supplies. While this can give the impression of low noise and resolution, that is often caused by their noise introducing harmonics that don't exist in the original content. This gives the impression of detail, but leaves much to be desired in terms of harmonic content, organic character, and natural musical flow. Because we have spent so much time on the power supply you will find that our system is not only the lowest noise you have ever heard, but also one of the most organic and musically engaging. No matter how good the switchmode power supply is, it'll be bandwidth limited to 1/5th its clock frequency, meaning all of that harmful noise that impacts digital the most will be left to destroy the integrity of your music.
We understand the importance of a jitter-free signal. Our digital amplifier has the benefit of isolating clock from power lines. This allows us to directly reclock the signal each step of the way as well as provide perfect power to our TCXO. This prevents the crystal from injecting grunge into your audio signals. Dedicated power supplies are used for the clock for better isolation, lower jitter, and better accuracy. Our clocks are 1ppm or better with as low as -169dB phase noise. That means it's lower jitter than many atomic clocks.
One of the unique benefits of our Fully Digital implementation is that THD does not change with power output. This means that you get the same low distortion at 1 watt as you do at full output. This keeps distortion curves extremely flat and sonic benefits exponential. This low distortion is thanks to our newly designed output filter and feedback circuit.
Volume is controlled either by remote or by rotary encoder via microcontroller. It's a high resolution, low distortion volume control with its own dedicated 3.3V power supply to eliminate noise and amplitude distortion on the PWM square wave.
Analog outputs are optional and designed specifically for use with a subwoofer. It is not recommended that you use this feature as a standalone DAC.
High Frequency vibration in audio electronics can wreak havoc on your sound. Microvibrations down in the nanosecond range create stray magnetic fields, which in turn create noise voltages in your component and limit dynamic range, resolution, and harmonic content.
We do not believe in "tuning" your equipment through the use of feet. Stillpoints will not change the tonal color of our equipment, instead it increases microdynamics, resolution, and spacial characteristics within the system quite dramatically.
We offer two footer options, both of which are a significant component upgrade. The Ultra SS (pictured right) offers one packet of stillpoints antivibration technology, so using 4 per component offers a total of 4 anti-vibration pockets. The ultra 5 (Left) offers 5 packets per footer and a total of 20 isolation packets per component. The ultra 5 is expensive, but the upgrade is the equivalent of tripling the price of our product.
The Stillpoints work as an isolation device. There are two paths for vibration to travel, from stand to component and from component to stand. The stillpoints offer separate paths for each type of vibration and have no direct vertical path from top to bottom. Instead they use ceramic bearings in a stainless steel housing to dissipate the microvibration as heat extremely rapidly. Unlike most isolation devices and footers, these footers work on ultra high frequencies rather than within the audio band, this is they key to successful vibration isolation. Their effect is simply incredible and certainly worth the price of admission.
A Kratos Digital amplifier in your system could be one of the largest transitions you make on your audio journey. A fully digital system can seem daunting, but when you realize that you require fewer cables and have implemented a system that is far lower distortion and less sensitive to tweaking you'll be glad that you can finally just sit back and enjoy your music.
1. Fully Digital High-end home audio system
2. Fully Digital Recording Studio
3. Fully Digital Active Amplification
* Specifications may be changed at any time without prior notice