The reviewer is giving his honest experience with the product and was not paid to write a favorable article. The gear was purchased due to interest and enjoyment in sound quality and in pursuit of gaining more knowledge about sound.
When first heard the ampsandsound Nautilus at CanJam 2021, I remember it made a striking impression. I had turned on Frank Sinatra and Hoobastank songs and recall the sound being highly resolving with strong tonal density, control, and having a ball-room like air; a very lively amplifier with an energetic expression.
I obtained the ampsandsound Nautilus after selling the Bigger Ben Rev 2 and Agartha 2021. I decided to get the Nautilus after a suggestion by Justin, who helped me navigate the ampsandsound brand and other product recommendations. I opted to get the best offering at ampsandsound and down-sizing from the amps I once had to own only one amp; however, I've now decided to keep the Kenzie and Nautilus and power them along with a preamp, the Garage 1217 Project Sunrise III, which increases the detail in the notes.
Many reviews on this website have been from my experience with ampsandsound. So far, I’ve reviewed the Kenzie OG Rev 2, Bigger Ben Rev 2, and Agartha 2021. I’ve enjoyed my experience with the products at ampsandsound, and this time, I have the Nautilus, a flagship offering.
I first saw Nautilus on the ampsandsound website around 2019 when I became interested in the Kenzie. It hadn't even crossed my mind to own one because of the price range and my situation at the time; it was more like something I might own when I was more mature or as I advanced in my financial situation or settling down with a home.
The Nautilus an amplifier built in a dual-mono layout into a single 12 gauge CNC steel chassis with bracing that supports the 44lb transformer without struggle. It has two power transformers, separate power supplies, chokes, and input transformers. The two amps have separate turret boards, with the shared component being the input tube, volume control, and outputs. The part selection was not constrained, and the most robust power transformers and widest/least distortion output transformers were employed.
The Nautilus has a classic and decidedly prosaic design, employing turrets and point-to-point wiring with no silicone, ICs, or regulators. This design is considered a standard-bearer of purest audio with an American sensibility. The Nautilus is designed and built in a way that few modern amplifiers are. It’s not due to intrinsic inferiority, but the Nautilus’ production process is impossible to rush and incredibly expensive. Some of the most familiar tube amps ever produced utilize this method, including; McIntosh, HK, Leek, Quad, & Western Electric. They demand to be played and are built to last a lifetime.
The Nautilus is a tube-integrated amp for personal audio users. It allows for five separate impedances to be selected for system matching and you can also select between headphones or speakers with a flip of a button in the back.
The Nautilus performance is made possible with the custom wound ultra-high quality output transformers, which provide excellent frequency extension and a flat response. Input transformers are used for reduced noise floor, greater clarity, and sub-bass response.
For the reference amplifier, ampsandsound paired with the finest coupling caps, Jupiter copper foil in wax caps, which increases the micro-detail retrieval.
The Nautilus also allows for a wide range of tubes, including 6L6GC, through KT90, but not the KT120 or KT150. The Nautilus came to me with a pair of KT88, a single 12AX7, and two 5AR4 tubes.
The Nautilus utilizes a single-ended Class A operation with zero feedback to provide the essence of sound, strictly old-school SET sound.
Keeping in mind that the sound is source-dependent, I've listed USB audio bridges or pre-amps which both help to enhance the detail in the notes. With the USB audio bridge like the Singxer SU-6, and a pre-amp, such as the Garage 1217 Project Sunrise III, the sound makes a definitive step towards greater note detail and clarity. For this review, I used the Singxer SU-6, Audio-GD HE-7, and Topping D90SE.
Paired with the warmer HE-7, there is a bloom to the soundstage sound, giving the sound a still-much-nuanced depth. With the D90SE alone, there is still much more detail to be discovered when paired with the Singxer SU-6; with the Audio-GD HE-7 Amanero 384 (stock option), the sound is still quite muddy to my ears.
For my second listen with the Nautilus, I chose the Sennheiser HD 650 with the Blu Swing & Shade - Jazzyster album. I was very impressed with the separation, impact, and detail. I noticed it was less energetic and sparkly from when the first time I heard it. It seemed more contained in the highs and matches more of my preferences.
The Nautilus uses Tetra tubes which have a thicker midrange, tonal density, and impact; and they kind of complement DHT or Direct Heated Triodes, which pull some of the mid-range back to allow the other ranges to have more presence. The Red October is the DHT equivalent of the Nautilus. I find both to be enjoyable to listen to, but I've yet to try the Red October.
I wasn’t surprised by how good the Nautilus sounded when listening again. From the looks of the Nautilus alone, you can tell its packing power. Everything sounded very natural, clean, and impactful. The decay is very good, alongside the resolution.
One thing that set the Nautilus apart for me was how spacious it sounded. The scenery is very lush. I was expecting a sound similar to the Bigger Ben since the tubes used are similar. I found that the Bigger Ben Rev 2 had a stage that was like being in a large concert hall. With the Nautilus, you get this effect as well, but it feels more focused and mature, sounding more organic and natural; the notes extend and resolve with every detail; the splash and impact are especially notable as well, as it sounded expressive, thorough, and refined through the note quality with excellent extension.
The tonal density stood out to me, and it’s like a smooth crescendo of music that fully extends and unveils the full depth of each note, especially with quality source components. Paired with a neutral DAC like the Topping D90SE, you get to hear every bit of detail as the Nautilus ripples the notes. This is noticeable in other amps with the D90SE too, but the sheer power that allows the details to follow through when paired with the Nautilus is highly satisfying. There is much more space and thoroughness in macro-detail and the atmosphere. Adding a pre-amp added to the micro-detail, which, without, there was less definition but more tonal density, bass presence, and general slam.
Depending on the rectifiers you use, the Nautilus can be a neutral amp; the 5AR4 makes the sound more neutral and fast to me, but with 5U4G, there's more ambiance and musicality, and the 5U4G could be described to be neutral "where it matters". I like the 5U4G because it gives the Nautilus a liquid, musical sound; it's backed with a rich macro ambiance where the details play with grace. The experience could be described as a lush and full listening experience. It's natural and controlled as the notes extend fully, giving it a strong character and life to the music.
The power behind the Nautilus is felt through the presence of the notes. Detail is given the power to give grace to the sound behind the flow of the sound. The Nautilus adds onto aspects of what makes the Bigger Ben unique but gives it more power to give it more resolution to boot. That being said, the Bigger Ben has its unique sound as well, it could be said that the Nautilus has more power to dig into the music with even more power and stage to give it more richness. That being said, I must add that I didn't really try the Bigger Ben Rev 2 with the KT 88 very much when I owned it, and I wonder what the Bigger Ben sounds like pushed with the tube it kind of came to me stock with.
So far, one of my favorite tube combinations is with the KT88, 5751, and 5AR4s. The combination provides a clean, slight bloom to the music that I found very enjoyable during my initial second listen. The highs are smooth, accurate, and completely unfatiguing to me; the mids are alive and full of character, and the lows are balanced, detailed and impactful when needed. The 5U4G with the KT88 and 5751 is an excellent alternative for a more laid-back sound.
Being a tube amp, there are many combinations available. Generally speaking, the 12AT7 has less gain and is an option for the 5751 / 12AX7. The 5751 / 12AX7 has more gain, which I found I didn't quite need with my headphones yet. With the base power of the Nautilus, I found that the 12AT7 works better because we can adjust the sound to have more dynamics with the volume control for more sensitive headphones.
Aside from USB audio bridges and the source DAC, I thought cables also brought significant changes in taming some regions where it felt like the treble might be too intense for my tests.
With the equipment that I have, I felt like all my headphones were more than adequately powered. The Sennheiser HD 600, 650, HIFIMAN HE 560, HE6SE V2, HE1000SE, and ZMF Verite all played with beautiful timbre and strength.
Something about an amplifier like the Nautilus and the reason I’d recommend it is that it’s the end-game of the Tetra tube family for personal use that provides a fun, liquid sound that is deep, and full of extension. It’s a commanding sound that is full in resolution; an amp with a strong depth in the notes with full decay, with tube options to adjust the speed and attack.
The Nautilus has a lot of power, and this allows any source you have to have strong control and expression of the sound.
It should be noted that it's possible you may enjoy the DHT sound of the 300B better and may opt for the flagship equivalent, the Red October.
I enjoyed all the headphones I listened to the Nautilus with and felt that the Nautilus brought a thorough, engaging sound. A headphone I particularly found interesting was the HE6SE V2. With the reputation of the HE6SE V2 performance being great with adequate power, I was very impressed with how the HE6SE V2 sounded.
I’m still discovering how different tubes sound, but so far, with the JJ KT88, TungSol 6L6GC, TungSol EL34, JJ 12AX7, TungSol 5AR4, and PSVane 5U4G, and available source components, I’ve been able to gather some impressions. The EL34 with the 5U4G has tight, lean bass, and accurate, sparkly highs. The KT 88 has a full sound with more bass presence to fully engage.
I remember having expressed that the timbre on the Agartha was one of the best I’ve heard from an amplifier. I’ve found that the Nautilus is of the highest quality and enjoyable, and in some respects, may even be preferred depending on the mood.
For some reason, I thought that the TungSol EL34, not having Coke bottle shape, would not have enjoyable bass; but it’s a great, quality bass that has timbre quality that perfectly meshes with the soundscape. That’s how powerful the Nautilus is; it gives shapes to notes and provides a nice, full ambiance.
I've heard of the classic American sound being described by Justin as being romantic. I feel like all of ampsandsound amps has this house sound. The Nautilus takes that sound and embodies it to the fullest. The sound is very classy, a grand listening experience. The Nautilus can take any headphone and power it with grace and control, and tubes can be configured to adjust the impact, timbre, or tonal density. Being the most resolving amplifiers I've ever listened to, there is no way that I could not recommend it; to me, it is a perfect companion to have for personal audio.