Built-In vs External Phono Stage
If you own a turntable, you need a phono stage. The question is whether to use one built into your amplifier or buy a standalone external unit. Both approach the same job — amplifying the tiny signal from a phono cartridge and applying RIAA equalization — but they do it differently, and the differences matter.
What a Phono Stage Does
A phono cartridge outputs a signal at a fraction of the voltage that other audio sources produce. A moving magnet cartridge outputs roughly 3 to 5 millivolts; a CD player outputs 2,000 millivolts. The phono stage amplifies the cartridge's output to line level (roughly 1 to 2 volts) so the main amplifier can work with it.
The phono stage also applies RIAA equalization — a standardized frequency curve that reverses the equalization applied during vinyl cutting. Without RIAA EQ, vinyl playback sounds thin and bass-less because low frequencies are cut during manufacturing to keep groove width manageable.
Built-In Phono Stages
Most vintage receivers and many vintage integrated amplifiers include a built-in phono stage accessible via the PHONO input on the back panel. Many modern integrated amps also include one. The quality varies enormously.
Pros: No extra box, no extra cables, no extra power supply. Simple and clean. Vintage Japanese receivers from brands like Yamaha, Pioneer, Sansui, and Marantz generally have competent to excellent built-in phono stages that were designed when vinyl was the dominant format. These were not afterthoughts — they were primary design considerations.
Cons: The phono stage shares the chassis with the power supply, output stage, and tuner (in receivers), which introduces potential interference. Built-in stages are almost always MM-only — no MC support. Upgrading means replacing the entire amplifier.
External Phono Stages
An external phono preamp is a dedicated box that sits between your turntable and any line-level input on your amplifier. You connect the turntable to the phono preamp's input, and the preamp's output connects to AUX, TAPE, or any other non-PHONO input on your amp.
Pros: Dedicated power supply and circuit board isolated from the amplifier's electromagnetic environment. Often supports both MM and MC cartridges with adjustable gain and loading. Upgradeable independently — you can improve your phono stage without changing your amplifier. Purpose-built circuits from specialist manufacturers often outperform the built-in stages in all but the best vintage gear.
Cons: Additional cost (from under fifty dollars to thousands), another box and power cable in your rack, additional interconnect cable between the preamp and amplifier.
Schiit Mani 2
$Adjustable gain (four settings covering MM and high-output MC), passive RIAA network for accuracy, and measured performance that embarrasses phono stages costing three times as much. The Mani 2 is the benchmark budget external phono stage. If your built-in phono stage sounds noisy, flat, or dull, this will be a revelation.
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iFi Zen Phono
$$MM and MC compatible with adjustable gain, impedance loading, and subsonic filtering. Balanced circuit design for low noise, plus an optional balanced output for amps that support it. The Zen Phono is a step up from the Mani 2 in flexibility and refinement.
When to Use Which
Use the built-in stage if your amplifier is a quality vintage unit (Yamaha, Pioneer, Marantz, Sansui) from the vinyl era and it sounds clean with no hum or excessive noise. These stages were engineered by people who knew vinyl was the primary source format. Spending money on an external preamp may not yield an audible improvement.
Use an external stage if your amplifier has no phono input, if the built-in stage is noisy or dull-sounding, if you want to use an MC cartridge with an MM-only input, or if you want the ability to upgrade your phono stage independently. An external preamp is also the right choice with modern integrated amps, where the phono stage is often an afterthought added for marketing rather than performance.
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Noise Floor and Signal-to-Noise Ratio
Phono signals are extremely small — a few millivolts from an MM cartridge, a fraction of a millivolt from MC. Any noise introduced during amplification is amplified along with the music. The phono stage's signal-to-noise ratio (SNR) determines how much background noise accompanies the music signal. Higher SNR means cleaner, quieter playback.
Built-in phono stages in vintage receivers share their chassis with power transformers, output transistors, and (in receivers) tuner oscillator circuits — all sources of electromagnetic interference. Quality vintage designs shielded the phono section with metal enclosures and careful grounding, but space constraints limited how much shielding was practical. External phono stages live in their own enclosure with their own power supply, free from the electromagnetic environment of the main amplifier.
In practice, the noise difference between a well-designed built-in stage and a quality external stage is often inaudible during normal music playback. The difference becomes apparent during quiet passages, in the silent grooves between tracks, and when listening through high-efficiency speakers that reveal background noise more readily. If you hear hiss or hum during silent passages on your vinyl setup, an external phono stage is likely to reduce it.
RIAA Accuracy
The RIAA equalization curve boosts bass and cuts treble during vinyl cutting; the phono stage reverses this curve during playback. The accuracy of this reversal determines tonal balance. A phono stage with poor RIAA accuracy will produce playback that sounds too bass-heavy or too bright, regardless of the cartridge or speakers in the system.
Quality external phono stages typically achieve RIAA accuracy within 0.2 to 0.5 dB across the audio band — essentially transparent. Built-in stages vary more widely; some vintage units with aged components may deviate by 1 to 2 dB in the bass or treble region. This deviation is subtle but audible to experienced listeners as a slight tonal imbalance that no tone control adjustment can fully correct because RIAA deviations are frequency-dependent, not a simple tilt.
Upgrade Path Advantages
One of the strongest arguments for an external phono stage is the upgrade path it enables. With a built-in stage, upgrading the phono section means upgrading the entire amplifier — replacing everything to improve one function. With an external stage, you swap out one small box while keeping your amplifier, speakers, and other sources unchanged. This modularity is the core advantage of separates thinking applied to the phono chain.
External stages also let you experiment with different cartridge types. If you start with an MM cartridge on a built-in MM-only input and later want to try an MC cartridge, you need an external MC-compatible stage regardless. Buying an external stage that handles both MM and MC from the start gives you flexibility to explore without additional purchases later.
Frequently Asked Questions
Is my vintage receiver's phono stage good enough?
Probably yes, if it is from a reputable brand (Yamaha, Pioneer, Marantz, Sansui, Kenwood) manufactured during the vinyl era (1970s-1980s). These receivers were designed with vinyl as the primary source and typically include competent to excellent phono stages. Listen for hum, noise, or dullness — if those are absent, the built-in stage is likely serving you well.
Will an external phono preamp make my vinyl sound better?
It depends on what you are replacing. An external preamp will noticeably improve sound if your current built-in stage is noisy, the frequency response is uneven, or it lacks the gain/loading options your cartridge needs. If your built-in stage already sounds clean and detailed, the improvement may be subtle or negligible.
Can I use an external phono preamp with my receiver's PHONO input?
No — never connect an external phono preamp to the PHONO input. The PHONO input applies RIAA equalization, and the external preamp has already applied it. This would double the equalization and produce distorted sound. Connect the external preamp to AUX, TAPE, CD, or any other line-level input.