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I purchased this unit from Safe & Sound HQ in Feb 2023; advertised as ‘open box’. Shipped in original packaging.The common quote about the M5si is true à it can pretty much power any speaker pairing you can throw at it.Warm, transparent, and muscular…bass is especially downright concussive.Features150 watts per channel into 8 ohms, configured internally as two independent monoblocs with a separate preamplifierDeveloped after the flagship Nu-Vista 800 and sharing some of its PCB layout solutionsMoving magnet phono stage, suitable for cartridges of 1.5mV output or moreincluding high-output moving coilsAsynchronous USB type B input accepting up to 24-bit/96kHzFour line-level RCA inputsFixed line-level output plus a variable preamp output for bi-amping or a subwoofer12V trigger in and outUniversal infrared remote supplied — volume, input select, mute, and transport control for a matching Musical Fidelity CD playerDistortion below 0.010% and better than 100dB A-weighted signal-to-noiseSpecificationsType: Stereointegrated amplifierPower Output: 150 watts per channel into 8 ohmsTHD + Noise: <0.010% typical, 20Hz – 20kHzSignal-to-Noise Ratio: >100dB A-weightedFrequency Response: +0, −0.1dB, 10Hz – 20kHzOutput Voltage: 35V RMS, 20Hz – 20kHz; onset of clipping at 99V peak to peakOutput Current: 62 amps peak to peak — see note belowDamping Factor: 36 (published in the owner’s manual, absent from the website specification table)Output Devices: 2 pairs per channelLine Input Impedance: 40k ΩInputs: 4x line level RCA; 1 x USB type B (asynchronous, up to 24-bit/96kHz); 1 x MM phono; trigger inPhono Type: Moving magnet only. Musical Fidelity states it suits cartridges giving 1.5mV or more, which includes high-output moving coil types. There is no MC settingPhono Sensitivity: 3mV nominal (MM)Phono Input Impedance: 50k Ω. Note this is Musical Fidelity’s own figure, published consistently on the product page and in the manual. The industry standard for MM loading is 47k Ω, so 50k is non-standard, but the audible consequence is negligible and we have reproduced it as published rather than corrected itPhono Signal-to-Noise Ratio: >70dB A-weightedPhono RIAA Accuracy: RIAA/IEC within ±0.5dB, 20Hz – 20kHzPhono Grounding: 4mm banana post to chassis earthDigital Inputs: USB type B only — there is no coaxial or optical inputOutputs: Trigger out; 1 pair fixed line level RCA; 1 pair variable preamp RCASpeaker Outputs: One stereo set on 4mm banana plug / binding posts (oneleft pair, one right pair). There is no A/B speaker switchingHeadphone Output: NoneRemote Control: Supplied. M5s series universal infrared handset covering volume, input selection (CD, USB, PHONO, TUNER, AUX1/HT, AUX2) and mute, plus transport functions for a matching Musical Fidelity CD player. Two LR03/AAA alkaline batteries suppliedMains Voltages: 115/230VAC 50/60Hz, factory pre-set; 100VAC 50/60Hz availablePower Consumption: <0.5W standby; 450 watts maximumSupplied Accessories: 10-amp IEC mains lead, remote control, 2 x AAA batteriesDimensions (W x H x D): 440 x 100 x 405 mm (17-1/3″ x 4″ x 16″), height including feet, depth including terminalsWeight: 14.6 kg (32 lb) unpacked; 18.8 kg (41.5 lb) in the shipping carton
This is a seller’s market for this category, but US$1,500 is still a fair ask rather than a stretch. Against your own recent comps, it lands above the US$1,280 median and below the US$1,575 75th percentile, so it sits in the upper-middle of the used range rather than in bargain territory.
That makes it a sensible buy if the unit is clean and complete. The M5si is well regarded for its big, authoritative sound, strong drive, and straightforward plug-and-play appeal, especially if you want a muscular integrated without fuss. At this price, the main thing to confirm is condition and completeness: remote, original packaging, and evidence it’s been treated gently all matter, since there’s not enough cushion here to ignore obvious wear.
Independent perspective — not a price guarantee. Always verify condition, accessories and provenance before purchase.
Musical Fidelity, a British hi-fi icon, traces its roots to 1982 when clarinettist and audio enthusiast Antony Michaelson founded the company in London. Disillusioned with the sound quality of existing gear after his stint at predecessor Michaelson & Austin, he handcrafted his debut product—a minimalist preamplifier dubbed "The Preamp"—on his kitchen table. Paired with the quirky Dr. Thomas power amplifier, these designs disrupted the market with their bold aesthetics and sonic punch, establishing Michaelson’s experimental ethos from the outset.
The brand has long centered on amplifiers as its cornerstone, spanning integrated, power, phono, headphone, and preamp models renowned for Class-AB topology and innovative touches like Nuvistor tubes. It expanded into streaming players, DACs, CD players, Bluetooth receivers, all-in-one systems, and even headphones and turntables, always prioritizing musicality over convention. Unconventional industrial designs, from curved heatsinks to sculptural panels, became signatures, influencing competitors.
Positioned firmly in the high-end arena, Musical Fidelity commands respect among discerning audiophiles for its value-driven performance and soulful sound. Iconic models like the A1 and F-series endure as collector favorites, blending accessibility with premium engineering. Acquired by Austria’s Audio Tuning in 2018, it continues evolving under new stewardship while honoring its heritage as a boutique force in British hi-fi.
See all Musical Fidelity listings on RADAR.
