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The name Agartha used to describe a city in the center of the world. The ampsandsound Agartha...

ampsandsound Agartha Single-Ended Amplifier

  • The name Agartha used to describe a city in the center of the world. The ampsandsound Agartha brings the legendary 300b to personal audio. We chose the 300b for its long history as the king of triodes. Combining a single gain stage, zero feedback and careful attention to grounding techniques we are able to use a 300b with headphones without hum or noise. For those with headphone, horns or single driver speakers who are seeking audio nirvana, the Agartha is built with exacting attention to parts selection and implementation.

Recent Reviews

  1. Dillan
    Ampsandsound Agartha: Silken Simplicity
    Written by Dillan
    Published Sep 28, 2016
    Pros - Classy aesthetics, plenty of power, impressively silent background
    Cons - No courtesy XLR, unique (sometimes annoying) port locations

    Ampsandsound Agartha: Silken Simplicity



    Tube amplifiers are a real hard thing to get right.
    Some people swear by these vacuumed vanities, while others prefer a modern (and technically superior) solid state approach. I think most people are somewhere in the middle and I would think I am part of that majority as well. I think the difficulty associated with tube based amplifiers come from aspects pertaining both a consumer and a manufacturer. I sort of imagine this category of audiophilia as taking a dart and giving it a hopeful toss towards a dart board. There are several things you have to get right from all angles for the sound to be a bulls-eye, but sometimes it happens.. and boy is it worth the chase.
    Ampsandsound is a very unique company building speakers and amps (hence the name) based out of California and led by a man named Justin. How ironic it is for a young man to build products that could've easily blended in 20 to 30 years ago. This isn't to say that what he builds is out of date, I actually think the proper way to describe these beautiful devices is "timeless". One of my first conversations with Justin was him encouraging me to open up his amplifiers and take a look inside myself - if that doesn't scream confidence then I don't know what does. If anything, the foundation of his design philosophy, attention to detail and openness as a whole demands respect and is a breath of fresh air in contrast to his big-name competitors.
    We will go into more detail about this interesting company and product in a bit, but first lets look at some measurements:


    Input Sensitivity: 840mV RMS for full power
    Max Power: 5watts RMS into 8ohms
    Max Power: 1.5watts RMS into 32ohms
    Noise: 760 uV as measured from 8ohm Tapp
    Noise: 660 uV as measured from 32ohm Tapp
    Power Bandwidth 20hz @ -.5db down to 20Khz @ -2db down as measured from 8ohm Speaker Tapp measured at 1 Watt RMS
    Power Bandwidth 20hz @ -.5db down to 20Khz @ -4db down as measured from 32ohm Headphone Tapp measured at 200mWat RMS
    Right from first glance you see that this is not only a headphone amplifier, but can comfortably power speakers as well. As you can see, the Agartha packs a punch and I personally had zero trouble providing adequate juice to all of my headphones using the Agartha. It is also worth mentioning that the Agartha not only gave enough power, but when paired with some of my more efficient cans, they gave just the right amount as well. The delightfully surprising noise floor and the fulfilling versatility had me licking my lips from the start.
    Keep in mind this is a single ended tube amplifier, so don't try comparing your balanced solid state's harmonic distortion down to the quintillionth.. Up and down the frequency range I found no unenjoyable roll-off in any direction, but this was affected by which tubes I used. Did I mention this is a classy 300B based tube design!? Taken from their website:
    "The Agartha tube amp pairs a 6SL7 tube for front end with SS rectification enabling great transient peeks, faster/livelier presentation and ultra-quiet operation. The Agartha uses direct-heated triodes with zero feedback providing the classic single-ended sound so widely loved."
    In general with the nature of vacuum tubes, specifications only tell you so much - I would highly encourage experimentation and listening first-hand before making decisions or forming opinions pre-listen. Changing tubes definitely influenced my listening experiences, as well as altered measurements.

    Build quality: Fire and wood!?​

    So in general I wouldn't recommend mixing fire and wood on your audio rack.. but in this case I certainly would! A glowing tube layout fixed into a sturdy black metal base wrapped in wood *gasp*! The build quality to the eye is stunning and to the hand is robust and durable. An accomplishment worth bragging about (and I don't mind to on it's behalf). In fact the first thing a few of my friends noticed when walking into the room was the Agartha resting atop the table. A head turner and compliment magnet. I think the appearance is actually quite aligned with the sound, which is pleasantly different from my experiences with other beautiful tube amps. I certainly won't discredit anyone specifically, but in my quest for tube nirvana, I have gravitated toward pretty and popular.. only to be disappointed when pressing play. We haven't quite gotten to sound yet, and the Agartha certainly isn't perfect, but it does walk the walk and talk the talk.
    Running my fingers across the walnut side panels gives every indication of smooth and sturdy construction. No loose screws, consistently clean lettering and you can run your hands against the gorgeous wood without getting a single splinter. Neat huh?
    This twenty-five pound beauty sits on rubber vibration agnostic black feet. As stated above, the core of the unit is a sturdy black metal wrapped in walnut. Each corner is complimented with ebony and altogether the black and wood design mesh extremely well together and demand appreciation. Unlike most headphone amplifiers, the Agartha has inputs and outputs on the top panel with no ports (not even power) on any of the four sides. An aggressive approach, reminiscent of high-end speaker amplifiers. At first I was reluctant to form an opinion on the fact that I had to plug all of my cables into the top. This could either create a distraction or an appreciation for your custom wiring.. who knows. What eased my concerns was a conversation with the designer himself. Assuring me of the simple and pure methodology behind the engineering in this design was enough to put me at ease. If the possibility of compromising sound just to add parts to move inputs/outputs around doesn't change your mind - I am not sure what will. I am still iffy about plugging straight terminations into the Agartha, but if your custom cable dealers offer right angle configurations, then I think that would flow perfectly with this particular amplifier design.
    Looking top-down you'll find a smooth-turning volume knob in the bottom left corner, sitting beside a 1/4'' headphone output to its right. The pair of 300B's hug the 6SL7 in the center, with components housed in black metal behind it, including a large choke among others. In the far back you'll find a simplistic array of RCA and speaker taps. I would have liked to see a few extra features such as an XLR output simply to utilize my upgraded cable. A lot of single ended designs are adding XLR just for the convenience factor, but I can see how this would conflict with the Agartha's attitude of less-is-more. The top right is your power plug and the bottom right is the power switch. While some aspects of simplicity can be frustrating, I definitely appreciate the purity in design.
    A fiery tube layout rests on well crafted wood panels. A campfire-like aesthetic that could intoxicate even the snobbiest design imperialist. I felt a strange attraction to the Agartha and the silver etched "ampsandsound" logo front-and-center was the cherry on top.

    The Quest for Best​

    I mentioned above the notion of experiments and hinted at synergy. I also noted how difficult it was to get a tube setup "right". I really can't stress these things enough.
    When you enter the world of analogue and/or physical audio reproduction you'll find inconsistency and you'll find frustration. The positive side to this is you'll also discover a sound that can actually be quite natural. A digital approach often times will look better on paper, but may sound worse. Why is this? Well because "digital" is the opposite of "natural". We are on a constant search for solid state technological feats with as little distortion and highest specs possible.. but in the real world, distortion is all around us. The term distortion often times has a negative connotation to it, but to an audiophile; distortion can be musically pleasing. This can lead to a more natural bliss for the listener, but it can be difficult to get to that point.
    How a tube is made and implemented will audibly alter sound reproduction for music flowing through it. This means different tube variations will create different sound signatures and that isn't even to mention how different the amplifier designs themselves factor the experience as well. So think of the difficulties matching the right amplifier to the right vacuum tubes using the right headphones. I feel like "synergy" is an overused term for audiophiles, but in this case it's an accurate description. It took me a long time before I realized the most important thing to know is where to start. Some amps will just plain never sound good. I have found through experience that some things might help a poorly built amplifier, but in the end you shouldn't ever upgrade a bad car.. you should just start with a good car and go from there.
    I won't go into tube rolling or how tube amplification works, but I will instead keep my focus on the Agartha and my experiences with it specifically. I did do some minor tube rolling and comparisons, but I will just explain the setup I liked best. Justin from ampsandsound was more than helpful in recommending me tubes based on my equipment and sound preferences and to my surprise, all the advice taken more than satisfied my needs perfectly. He is definitely a person who doesn't just see his customers as disposable, but puts in a continuous effort to customize your needs for a positive experience.
    So lets dive right into it:
    Headphones: Audeze LCD-4, Audeze EL8 open, Grado RS2e
    Cables: Almost exclusively Plussound audio silver plated copper cabling
    DAC: PS Audio Directstream
    Source: Jriver FLAC/DSD via laptop
    Power: PS Audio P5 Power Plant
    Tubes: Primarily 2x Electro-Harmonix Gold 300B & Tung-Sol 6SL7
    Again, I will try to be as descriptive as possible in a manner that notates the overall sound of the Agartha regardless of tube specifics. I will describe the sound that was persistent regardless of tubes used. Before beginning I would like to say that the foundation of the Agartha's sound signature is so respectable and refreshing. No other amplifier in my experience has had this much versatility and enjoyability. I would never recommend a certain style of headphone to pair with this amplifier, because nothing should be assumed exclusive. This amplifier satisfied my listening needs with any headphone I used (albeit better matched with certain tubes than others). I did not test my Kaiser K10 or other highly efficient in-ears, because this amplifier is not built for them. It is possible a good match may exist, but I didn't want to try something that goes against what this was built for. Without even trying that pairing - I personally advise against buying the Agartha to drive something other than small speakers or full sized headphones.
    To be blunt: for those who do not describe themselves as tube junkies, do not hesitate or fret. Call or email an ampsandsound employee and tell them your preferred sound signature and the headphones or speakers you plan to use with the Agartha and you should be at ease knowing the recommendation you are getting from them will be top notch.


    Bass: The bass had an authoritative softness to it. I know that sounds counterproductive, but it's not. The way I would describe it is instead of a crisp bang that I normally heard from my solid state Vi Dac amplifier - I heard a rich bloom instead. The bass would not attack your ears as much as it would envelop them. Although the bass is unique and rich, I wouldn't call it the most appealing aspect of the sound. I did feel myself slightly disappointed during drum solos that should've sounded more energetic, but instead felt romantic in a sense. Bass heads might be a little bored of the bottom end. However the engaging nature of the bass during slower music was definitely satisfying. Although I didn't particularly enjoy drum playing, I did enjoy deep tones from stringed instruments such as a cello. These sounds flowed well with the musical spin the Agartha put on bass reproduction. Electronically produced bass, or drum playing left me preferring other options. The bass did linger slightly, but overall the decay felt organic to the music. Around 50hz I felt the most presence, but overall I think the bass is pretty extended.
    Midrange: You know that kid who always plays well on a winning sports team, but doesn't get enough credit? That is how the midrange can be described. The Agartha has a consistent, accurate and detailed midrange. I can't think of any characteristic that stands out in a negative way, or even a positive way. The mids just sound right, through and through. Frank Zappas "Muffin Man" has a very complicated assortment of sounds, all of which the Agartha played with ease. In fact I would say instrument reproduction is very effortless in this range and voices share the same lush softness that the bass has. Something so consistent and effortless is hard to describe, but one thing that did impress me was the positional accuracy. I knew where every voice and instrument came from, especially when in the mid frequencies. I think the mids have a neutrality that some people might really respect, especially considering the accurate nature on top of that. That neutrality is only slightly influenced by a warmth, but mostly uncolored and accurate. Simple yet effective.
    Treble: There is a slight roll-off at the very top. Electronic music especially lost the sharpness that you would normally expect. This did sound exceptionally pleasing with some of my brighter headphones, but not so enjoyable with my dark headphones. I say that first, because it's something you should definitely expect with this amplifier. If you want a completely crisp and clean top end, then I would look elsewhere. Saying that - I did love the treble. My LCD-4 had a tough time with the Agartha, because these headphones already have a confusing top end to begin with. However my brighter Grados felt right at home. The sparkle of my RS2e was complimented very well with this amplifier. I can imagine the HD800 would have a more disciplined high frequency response with this pairing (and in a good way). Objectively I think it may be wrong to say the Agartha has an awesome treble area, but subjectively it can be incredible. Partnering the right headphones is a must with these, but I can't express a negative response when the right headphones sound so perfect. I can definitely appreciate the fact that the treble has a balance between constraint and articulation. The perceived roll-off is just enough to make things comfortable for the majority of listening. My personal experience has shown a natural sound to lean more towards the dark side of things as opposed to the sibilant side. This is definitely the case in the Agartha's high frequency response; dark yet natural. Netsky's "Go 2" was a very fun and engaging listen. The crisp electronic cymbal sounded more "real" than what I was used to. Although I would definitely warn anyone not to match an already dark headphone with this amp - I think the majority of headphones will love the higher tones played. It's difficult to describe the exact signature, but the initial appreciation was when playing Chet Bakers "Live in Paris" album. Instead of wincing during some of the higher toned trumpet playing, I heard a realism with perfect decay. Through the entire spectrum surrounding 8khz I heard accuracy I have never heard. It was like I was up close and personal during the upper mids, but the warmth of the treble reproduction distanced me during treble spikes that would normally be uncomfortable. There wasn't any veil at all, only perhaps some perceived darkness depending on song and gear. Soft clarity all the way through.
    Overall: Instead of further breaking down each category of sound, I could paint a better picture giving you an overall description. The Agartha definitely has forced sounding reverb, but not unpleasantly so. The overall mix between its soft nature, pinpoint accuracy and splash of reverb gave me quite a distinct sound that I have never heard before. What a unique experience! It is almost impossible not to imagine in your head exactly where each instrument and sound is coming from. Upon first listening I thought the sound signature was too "distant", but this turned into the realization that the imagery and soundstage is just that significant. I am not sure if there is some sort of crossover going on in the internals, but listening to the Agartha with headphones almost tricks your brain into thinking there are speakers in front of you.. and in some cases the band or artists themselves. The Agartha has natural euphonics, distant musicality and softness that creates a cocktail of indulgence that is really hard to resist. With my LCD-4 I felt the pairing was less than ideal, which ultimately made me a little sad. I know the capability of the Agartha and with the right headphone I believe this is one of the best sounding headphone amplifiers on the market today. With the LCD-4, an overly dark sound filled your ears to the point of even brightly recorded tracks sounding muddy and veiled. The lushness of the headphones mixed with the richness of the amp just became "too much to handle". However the RS2e and even the SR80e were an extremely enjoyable match with the Agartha. Creating an open, accurate and pleasing experience. Instruments became so much more comfortable sounding, without sacrificing detail. In fact, regardless of the almost perfect instrument separation and imagery - the Agartha still introduced engaging coloration that just made for one of the most natural sounding amplifiers I have ever heard. This situation is one that rewards synergy and careful combinations. You can punish your ears with the wrong headphone, but the limitations of potential are almost nonexistent. This beautiful wooden amplifier from ampsandsound definitely has left me impressed and a little starry eyed.
    Although I loved experimenting with the Agartha, the most impressive part of the entire experience wasn't listening to this magical device.. it was talking to the owner. Justin treats his customers like family, which is incredibly rare to see these days. The potential of his products do not feel wasted when you have such an open, honest and engaging designer helping you along the way. I was lucky enough to be able to do a short Q&A with Justin for the sake of my review and you guys, the readers. Let's see what he has to say!

    Questions and Answers​

    My first question is where did you learn to build amplifiers and audio products?
    Where did it all begin? I started with disassembling amplifiers and trying to put them back together. I bought old gear and tried to get them up and running. Later I turned to rebuilding Dynaco amps. I still maintain a soft spot for dynaco gear and the reproductions where I started. That said, sites like audiokarma, and diyaudio were super helpful as well as pointing me to more formal resources like the RCA receiving tube manual and the NEETS - Navy Electricity and Electronics Training Series. With all that said ampsandsound has always utilized a collaborative approach. We’ve partnered with gifted designers to bring traditional tube circuits back.
    What made you start your company ampsandsound? How was the transition from hobby to business?
    ampsandsound made the jump from hobby to business about 4 years ago. The volume of amplifiers we were producing was sustainable in the true "made by hand" manufacture process. We used to drill each chassis by hand. This approach had many short comings. When we decided to start using top plates ampsandsound as we know it was really born. This meant translating existing ideas to a new process and working through the process. The move to CNC top plates mean that each amp could be 100% repeatable without human error that hand drilled chassis introduced. Ive always built high value SE tube amps that were paired to horn load speakers. As the market has changed from an emphasis on speakers to personal audio my lower power designs were less favored. After a lot of experimentation, I discovered that many of these designs would pair well to headphone. Many of the cutting edge headphones today demand reasonable power. Pairing low power single ended designs with these headphones brought Japanese purist audio to personal audio. 
    On the same token - What separates ampsandsound from other boutique audio companies?
    ampsandsound takes traditional tube circuits, pairs them with modern material science; to achieve our steller results. We utilize high tolerance components which only years ago were too expensive to practically use as well as wide bandwidth transformers and PCBs for repeatability and ease of servicing. We try to take proven well regarded designs and make them as simple and well produced as possible. We exclude features or options which may add ease, but additionally add complexity. We describe this as purist audio with an American aesthetic.
    What was your vision behind the Agartha and how did it get its name?
    The Agartha is an amplifier meant for those who seek tradition. It utilizes probably the most widely known triode in existence, the 300b. It is the quintessential tube amp, single gain stage, single ended, class A, directly heated triode, and no feedback. The approach provides with the realism and truth in the midrange that is so often sought. It additionally means that it has significant limitations including high frequency ext and power. We could have chosen additional gain stages or feedback which would have given the Agartha more power and a more modern sonic profile, but we chose to build an amplifier which is a reference point, a true north for sonic purity.
    Whats next for ampsandsound? What can we look forward to seeing from you guys in the future?
    We have line and phone stages that we have kept under warps for a long time. Providing an option for MM turntable to be paired directly to our headphones really excites me. Additionally, we will continue to develop amplifiers which provide more options to the customer. We want the Mogwai or Agartha you use now for your headphones to grow with you. When you have an apt or home, pair them with speakers and continue to enjoy that same sonic profile you’ve come to love. 


    I am still a little in awe of the entire experience of speaking with Justin, unwrapping and listening to the Agartha and writing this review. It really is hard to describe something that doesn't stand out in any particular way, but in fact does almost everything right at the same time. If I had to pinpoint my favorite part of my listening sessions, it would definitely be listening on my Grado RS2e and EL8 and hearing the incredible singing voices of Gregory Porter, Stevie Wonder and many more. The midrange is really worth calling amazing. Violin, cello and voice reproduction are the highlights of my listening with the Agartha and I am proud of the opportunity. I have bought many audio products before, but a personal relationship you build with a great company and owner are something you rarely see. You can gravitate towards big name brands all you want, but in my opinion you lose something special going that route. You lose attention to detail, you lose out on a more personalized experience and you lose the overall quality that you'd otherwise be gaining with a company such as ampsandsound. The Agartha for me was something truly unique and special and I hope to see more out in the wild soon!
    Considering price ($3600) I would give 4.0/5 stars and without price in the equation I give 4.7/5.
    Thanks for reading!
    Reviewed by: Dillan​
      PATB and WilliamLeonhart like this.
    1. View previous replies...
    2. Dillan
      Thank you :D
      Dillan, Sep 29, 2016
    3. Saillaw
      Nice review, thanks for writing it!
      Saillaw, Oct 5, 2016
    4. RCBinTN
      Very interesting.  Nice review, Dillan.  Looks like an excellent amplifier.
      RCBinTN, Oct 7, 2016


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