Musical Fidelity - M6si Integrated Amplifier

220 watts per channel, a balanced XLR line input, switchable MM/MC phono and asynchronous USB — the amplifier that has anchored the M6 range for over a decade.

Musical Fidelity describes the M6si as, in effect, a preamplifier with two monobloc power amplifiers that happen to share the same casework, and the specification supports the claim: 220 watts per channel into 8 ohms, distortion below 0.007% across the band, better than 107dB of A-weighted signal-to-noise, and a response held to +0/−0.1dB from 10Hz to 20kHz.

It is unusually well connected for its generation. Four line-level RCA inputs, a balanced XLR line input, a switchable MM/MC phono stage with a rear-panel cartridge selector, and an asynchronous USB type B input handling up to 24-bit/96kHz. That USB socket is the only digital input — there is no coaxial or optical connection. Fixed line-level and variable preamp outputs allow bi-amping or the addition of a subwoofer, and 12V trigger in and out are fitted. As with the M5si there is one set of speaker terminals rather than A/B switched pairs, and no headphone socket.

One point deserves plain speaking, because it is the single most likely source of disappointment. Musical Fidelity publishes a single phono input impedance figure of 47k ohms covering both MM and MC modes. Independent bench measurement of the M6si found roughly 40k ohms in MM and roughly 17k ohms in MC — so the two modes do load differently, and neither is 47k. Even 17k sits far above the 50 to 1000 ohm range most low-output moving coils are designed to see, and the M6si offers no loading adjustment. If you are matching a specific low-output MC, talk to us before you buy rather than after.

A universal infrared remote is supplied, duplicating the front-panel volume, input and mute functions and adding transport control for a matching Musical Fidelity CD player. The M6si remains a current product, offered alongside an M6si Chrome Edition, though it is no longer the newest M6 integrated — the M6xi arrived in 2026 with more power and a proper array of digital inputs.

Features

• 220 watts per channel into 8 ohms — a preamplifier and two monobloc power amplifiers in one chassis
• Switchable MM/MC phono stage with a rear-panel cartridge selector
• Balanced XLR line input in addition to four line-level RCA inputs
• Asynchronous USB type B input accepting up to 24-bit/96kHz
• Fixed line-level output plus a variable preamp output for bi-amping or a subwoofer
• 12V trigger in and out
• Universal infrared remote supplied, duplicating the front-panel controls and adding CD transport functions
• Distortion below 0.007% and better than 107dB A-weighted signal-to-noise
• Also offered as the M6si Chrome Edition

Specifications

• Type: Stereo integrated amplifier
• Power Output: 220 watts per channel into 8 ohms
• THD + Noise: <0.007% typical, 20Hz – 20kHz
• Signal-to-Noise Ratio: >107dB A-weighted
• Frequency Response: +0, −0.1dB, 10Hz – 20kHz
• Output Voltage: 42V RMS, 20Hz – 20kHz; onset of clipping at 120V peak to peak
• Output Current: 45 amps peak to peak — see note below
• Damping Factor: 180 as published by Musical Fidelity in the owner’s manual. The figure is absent from the website specification table, and independent measurement returned only 35 to 44 across the audio band. We publish it as the manufacturer’s claim rather than as measured fact
• Line Input Impedance: 40k Ω (RCA). Musical Fidelity publishes no separate figure for the balanced XLR input
• Inputs: 4 x line level RCA; 1 x line level XLR balanced; 1 x USB type B (asynchronous, up to 24-bit/96kHz); 1 x switchable MM/MC phono; trigger in
• Phono Sensitivity: 3mV nominal (MM); 0.4mV nominal (MC)
• Phono Input Impedance: 47k Ω. Musical Fidelity publishes this single figure for both MM and MC. Independent measurement puts the actual loading at approximately 40k Ω in MM and approximately 17k Ω in MC, so the modes do differ and neither is 47k. There is no adjustable MC loading, and 17k is far higher than most low-output moving coils expect — check cartridge matching with us before purchase
• Phono Signal-to-Noise Ratio: >84dB A-weighted
• Phono Distortion: 0.01%
• Phono RIAA Accuracy: RIAA/IEC ±0.5dB, 20Hz – 20kHz
• Phono Mode Selection: Rear-panel MM/MC cartridge selector switch
• Digital Inputs: USB type B only — there is no coaxial or optical input
• Outputs: Trigger out; fixed line level output; variable preamp output
• Speaker Outputs: One stereo set on 4mm banana plug / binding posts (one left pair, one right pair). There is no A/B speaker switching and no dedicated bi-wire terminal set
• Headphone Output: None
• Front Panel: On/off, volume knob, input selector buttons with LEDs (CD, USB, PHONO, TUNER, AUX1/HT, AUX2, BALANCED), infrared receiver
• Remote Control: Supplied. Universal infrared handset covering volume, input selection and mute, plus transport functions for a matching Musical Fidelity CD player
• Mains Voltages: 115/230VAC 50/60Hz, factory pre-set; 100VAC 50/60Hz available
• Power Consumption: <0.5W standby; 58W idle; 680 watts maximum
• Supplied Accessories: 10-amp IEC mains lead
• Dimensions (W x H x D): 440 x 125 x 400 mm (17-1/3″ x 5″ x 15-3/4″), height including feet, depth including terminals
• Weight: 16.6 kg (36.5 lb) unpacked; 21.3 kg (47 lb) in the shipping carton
• Warranty: Two years, administered by the local national distributor — Harmonia Distribution has handled Musical Fidelity in the United States since 15 November 2025. Cover is for the original owner only, is non-transferable, and requires the original sales invoice as proof of purchase date. Older Musical Fidelity literature quoting a five-year term with separate categories for disc players and servers is obsolete
• Country of Manufacture: Not published. Musical Fidelity was founded in London in 1982 and has been owned since 2018 by Audio Tuning Vertriebs GmbH of Austria, the parent of Pro-Ject. The company states that its products are designed and voiced in the UK and continental Europe, which is a design statement rather than a manufacturing one, and it publishes no country of manufacture for this model
• Not Published: Power output into 4 ohms; channel separation; line input sensitivity; the USB receiver or DAC chipset; separate MM and MC phono input impedance figures; MC loading options; phono overload margin; balanced XLR input impedance
• Note: Musical Fidelity credits the 220W M6si with 45 amps peak-to-peak output current but the smaller 150W M5si with 62 amps. The relationship is backwards and one of the two figures is almost certainly wrong in Musical Fidelity’s documentation. Separately, the M6si product page renders phono RIAA accuracy with a reference extending to 50kHz while the owner’s manual states 20Hz to 20kHz; we have used the manual