Nautilus XL SE

The Nautilus XL SE stands as a counter point to our flagship The Red October XL SE Audio Tubed Integrated Amplifier.

The Nautilus XL SE is the second major evolution of our most beloved amplifier, built on years of refinement and hard work. The Rev 2 marked a turning point, bringing together our advances in power supply design with improved ergonomics. It was a watershed product we thought would stand as the high point for years to come.

The XL SE wasn’t planned. It grew out of a collaboration with a respected tube manufacturer who challenged us on filament regulation. That single idea changed the course of development and ultimately led to the Red October XL SE, which delivered performance we didn’t think was possible. With that success, we turned our attention back to the Nautilus, determined to bring the same goals to our most loved platform.

Nearly every transformer inside the Nautilus had to be reimagined. New power transformers and filament chokes were created, driving a 40 percent reduction in an already ghostly noise floor. This pursuit of silence became the foundation of the XL approach: lowest possible noise floor paired with extended frequency response. The result is astonishingly quiet operation, effortless power, and bass extension that feels bottomless.

Still, the Nautilus XL SE holds onto what made the original special. It carries forward the classic American sound with a touch of midrange emphasis, the kind of voicing that conveys intimacy and presence. This isn’t sound from a distance. It’s raw and alive, placing you right at the microphone where every breath and every ounce of emotion comes through.

The Nautilus is a dual-mono amplifier built into a single chassis. We started with our most versatile circuit, the Mogwai, and set out to create two independent amplifiers that share only the input tube, volume control, and outputs. Each channel has its own power transformer and power supply, built on separate turret boards, with every part chosen for performance. 

To support this design, we partnered with our CNC fabrication house to build a 12-gauge steel chassis with heavy bracing strong enough to carry the 44 pounds of transformers. In total, the Nautilus weighs 74 pounds before packing. A polished chrome cover finishes the build, protecting the transformers and giving the amplifier its distinctive presence.

The Nautilus follows a classic approach to amplifier design. It uses turret boards and true point-to-point wiring, with no silicon, ICs, or regulators. This method is demanding and expensive to build, but it connects the Nautilus to the tradition of legendary amplifiers. These were amplifiers made to be played and built to last a lifetime.

For flexibility, the Nautilus uses dedicated transformer taps rather than voltage dividers. This provides proper system matching across a wide range of headphones, with five selectable impedances available, along with a pair of 8-ohm speaker outputs. A simple toggle on the rear panel makes it easy to move between speakers and headphones without rewiring.

The heart of the Nautilus lies in its transformers. Custom-wound output transformers provide excellent frequency extension and a flat response, while input transformers handle XLR to RCA conversion. This lowers the noise floor, improves clarity, and extends bass response. We paired these with Jupiter copper foil in wax coupling caps, chosen for their ability to reveal fine detail. Volume control is managed with a 24-step stepped attenuator, ensuring precise channel balance.

The result is a reference amplifier that balances purity of design with an unmistakable American voice. The Nautilus delivers a sound that is intimate, powerful, and enduring.

The Nautilus utilizes a single-ended Class A operation with zero feedback to provide the essence of sound, strictly old-school SET sound.

Bench report with 12AX7 inputs with 5ARA4 rectifiers and KT88's

Input sensitive: with 12AX7 input @ 1.4V P-P on SE input

Max Power @ 8ohm  @ 8watts RMS with KT88s and 5AR4s

Max Power @ 32ohm@ 5watts RMS

Max Power @ 100ohm @ 6watts RMS

Max Power @ 300ohm @ 6watts RMS

Ultra-wide bandwidth: 18 Hz to 20 kHz -3 dB

Noise: 90uv RMS

THD: 0.4%

SINAD: 47 dB

THD+N: 0.4%

Compatible with nearly every headphone.

Power and Noise specs are dependent on tube selection. 

Actual size is 13”deep, 19” wide and 8”tall.(106lbs)

Amp weighs in at 106lbs/ 126lbs shipped in a large Pelican style case.

Black Base/Matte Black Cover, Black Mesh. 

Additional colors are possible as a special order... please call or email for details.

All ampsandsound amps are handmade in Southern California with custom hand-wound output transformers and U.S. sourced parts.

Our amps are hand-made by a small team with quality being our first priority.

Additional colors are possible as a special order... please call or email for details