Musical Fidelity Fx Power Amplifier May 2026

| Amplifier | Power (8Ω) | Character | Price (used) | Notes | |------------------------|------------|------------------------------------|--------------|------------------------------------| | Musical Fidelity FX | 50W | Warm, musical, forgiving | $150–250 | Vintage charm, needs check-up | | NAD 3020 (power amp section) | 20W | Warm, soft bass, very musical | $100–200 | Less power, even warmer | | Rotel RB-970BX | 60W | Neutral, slightly lean, detailed | $150–250 | More neutral, better treble | | Audiolab 8000P | 100W | Clean, punchy, high damping | $300–450 | More power, less character | | Modern class D (e.g., Aiyima A07) | 50W | Ultra-clean, dry, high detail | $80–120 new | More accurate, less musical charm |

Verdict: The FX is not the most powerful, nor the most transparent, but its euphonic midrange and fatigue-free sound give it a loyal following among vintage enthusiasts.

Audiophiles love acronyms, and "LSD" stands for "Loud Speaker Driver." The FX-LSD is a monoblock version of the concept. It takes one FX channel and puts it in a vertically oriented chassis. If you find a pair of these, you have a dual-mono setup that rivals amplifiers costing ten times as much. It offers 50 watts into 8 ohms and, crucially, doubles that into 4 ohms—a sign of a genuinely robust power supply. musical fidelity fx power amplifier

The main smoothing capacitors (typically 2x 10,000 µF or similar) can dry out, leading to increased hum, reduced bass, or a “tired” sound. Replacement with modern, higher-quality caps (e.g., Nichicon KG, Mundorf) is a common upgrade.

The original FX-A1 is a stereo power amplifier rated at a conservative 20 watts per channel into 8 ohms (35 into 4 ohms). Before you scoff at "only 20 watts," recall that Musical Fidelity’s legendary A1 integrated amplifier was also 20 watts. The FX-A1 is essentially a pure power amp version of that classic topology. It utilizes Class A/B operation running into heavy Class A bias for the first several watts—meaning for normal listening levels, it operates as a Class A amplifier, eliminating crossover distortion entirely. | Amplifier | Power (8Ω) | Character |

The FX power amplifier employs a class AB output stage. Unlike the single-ended class A design of the A1, the FX uses a push-pull configuration to achieve higher output power with better efficiency. The circuit is based on discrete transistors (no op-amps in the signal path) and features:

For the DIY-minded, the FX responds well to careful modifications: Warning : Mains voltages are lethal

Warning: Mains voltages are lethal. If you’re not experienced with electronics, take the unit to a qualified technician.

Especially around the transformer, speaker terminals, and input RCAs. Cracked joints cause intermittent channels or buzzing. Reflowing with fresh solder usually solves it.