Musical Fidelity - MF-XTUBE - Tube Buffer

Musical Fidelity X-Tube – The Missing Link in Modern Audio Systems

The Musical Fidelity X-Tube is a revolutionary tube output buffer designed to enhance the performance of modern digital and analogue audio sources. Housed in a newly reimagined X-profile aluminium die-cast chassis, the X-Tube marks the return of a legendary design concept first introduced with the iconic X10D.

Built as a pure Class A triode tube line stage, the X-Tube is engineered to maximise signal transfer, improve impedance matching, and introduce the unmistakable musicality of tubes—without adding measurable distortion or noise.

From X10D to X-Tube: A Modern Revival

The original X10D, designed by Musical Fidelity founder Antony Michaelson, was conceived as an “eXtended” signal stage—an intermediary buffer placed between source and amplifier to unlock hidden performance.

The new X-Tube faithfully follows this proven circuit philosophy while updating the mechanical design and power supply architecture. The external PSU has been eliminated and integrated directly into the chassis, resulting in a cleaner, more practical system layout.

Connectivity is intentionally simple:

• 1 × RCA input

• 1 × RCA output

• RCA bypass

The X-Tube sits transparently between source and amplifier, extending the signal path and allowing connected devices to perform at their full potential.

Why a Tube Output Buffer Still Matters Today

The Problem with Modern Digital Sources

Today’s streamers, DACs and CD players often excel in software and digital processing, but frequently compromise on analogue output stages to meet aggressive price points. Low-cost integrated IC solutions struggle to properly drive real-world amplifier loads, particularly when cables and varying impedances are introduced.

The X-Tube Solution

The X-Tube addresses this bottleneck by acting as the perfect electrical interface:

• High input impedance eases the load on weak output stages

• Low output impedance confidently drives any amplifier input

• Stable, non-reactive loading allows source devices to operate optimally

The result is improved clarity, dynamics, tonal density and spatial presentation—without altering frequency response.

The Audible Benefits of the X-Tube

Warmer, More Natural Sound

Tube circuitry naturally emphasises even-order harmonics, which are perceived as smoother and more musical than the odd-order harmonics common in solid-state designs.

Improved Dynamics and Transient Response

The X-Tube’s single-ended triode configuration allows for fast transient handling, delivering greater realism and expressive impact.

Reduced Listening Fatigue

The smoother tonal balance and harmonic structure result in a more relaxed, engaging long-term listening experience.

Greater Air, Depth and Imaging

Listeners often report a more expansive soundstage, improved instrument separation and a heightened sense of space.

Applications: The Missing Link in Action

CD Players and DACs

Adds tonal richness, depth and musicality to digital sources.

Streamers

Compensates for compromised analogue output stages found in many modern streaming devices.

Phono Stages

Improves impedance behaviour and reduces cable sensitivity for analogue sources.

Preamps and Power Amps

Provides ideal impedance matching when preamp and power amp compatibility is uncertain.

Home Theatre Systems

Enhances front left and right channels in A/V receiver and multichannel amplifier setups for high-fidelity stereo playback.

Technical Performance – Measured, Not Mythical

Despite its tube architecture, the X-Tube delivers exceptional measured performance:

• Distortion (10Hz–20kHz): < 0.003%

• Residual noise: Better than 96dB (unweighted)

• Frequency response: 20Hz–80kHz (+0 / −0.3dB)

• Crosstalk: Better than 95dB

In practice, the X-Tube introduces no audible distortion, no added noise, and no frequency response deviation—often outperforming the source devices it supports.

Inside the X-Tube: Technical Design Highlights

• 2 × E88CC (6922) triode tubes

• Single-ended, pure Class A operation

• High input impedance / low output impedance topology

• Excellent isolation from reactive loads

• Enhanced transient speed and signal stability

This elegant tube design provides impedance matching, electrical isolation and tonal refinement in a single, compact component.

The X-Tube at a Glance

Tube Output Buffer & Impedance Matching Amplifier

• Enhances all digital and analogue sources

• Ideal upgrade for budget DACs, streamers and CD players

• Optimises preamp-to-power amp matching

• Integrated mains power supply (no external PSU)

• Iconic X-profile aluminium chassis

Sound Character

• Warmer, denser midrange

• Improved dynamics and clarity

• Larger, more stable soundstage

• More vivid and engaging presentation

The Future of the X-Series

The X-Tube is the first in a new generation of Musical Fidelity X-Series products, reintroducing a mechanically inert, resonance-free aluminium enclosure combined with modern engineering refinement.

For listeners seeking to unlock the full potential of today’s digital sources while enjoying the timeless musicality of tubes, the Musical Fidelity X-Tube is the essential missing link.