This Focusrite ISA One Analogue Mic Preamp combines Focusrite's highly regarded transformer-based ISA microphone preamplifier with an installed ISA ADN2 Dante digital expansion card, substantially expanding its usefulness in modern studio and network-audio environments.

At the heart of the ISA One is Focusrite's classic ISA transformer microphone preamp, derived from the original ISA 110 design and equipped with a Lundahl input transformer, up to 80dB of microphone gain, selectable input impedance, high-pass filter, insert facilities and an independent instrument DI path.

This particular example has the optional ISA ADN2 digital card already installed, an upgrade worth £379, providing high-resolution digital conversion together with Dante, ADAT, AES3, S/PDIF and Word Clock connectivity at up to 24-bit/192kHz.

Presented in Very Good Condition and supplied with a hardcase, this is a particularly well-equipped ISA One for professional recording, project studios, location work and Dante-based audio systems.

At A Glance

Detail	Specification
Brand	Focusrite
Model	ISA One Analogue
Type	Transformer Microphone Preamp / DI
Mic Preamp	ISA Transformer-Based
Input Transformer	Lundahl
Mic Gain	Up to 80dB
DI	Independent Instrument Input
Digital Expansion	ISA ADN2 Installed
Dante	Yes
Max Digital Resolution	24-bit / 192kHz
Additional Digital Outputs	AES3, S/PDIF, ADAT
Word Clock	Input & Output
Condition	Very Good
Included	Hardcase
Dante Card Value	£379
Main Appeal	Classic ISA analogue preamp with modern networked digital output

Condition Overview

Very Good Condition

This Focusrite ISA One is presented in Very Good Condition.

Under the Fair Deal Music grading system, Very Good Condition means the unit shows some cosmetic wear consistent with careful previous studio use while remaining fully functional.

A particularly important feature of this example is the ISA ADN2 Dante expansion card already installed.

What's Included?

✔ Focusrite ISA One Analogue Mic Preamp
✔ ISA ADN2 Dante Digital Expansion Card – Installed
✔ Hardcase
✔ Internal Mains Power Supply

No additional accessories are included unless pictured or stated.

Installed ISA ADN2 Dante Expansion Card

This ISA One has already been upgraded with the Focusrite ISA ADN2, an optional digital conversion card valued at £379.

The ADN2 takes the analogue output of the ISA One and provides high-quality digital conversion at up to:

24-bit / 192kHz

Digital Connectivity

The installed card provides:

• Dante Primary network port
• Dante Secondary network port
• AES3 digital output
• Coaxial S/PDIF output
• Optical ADAT output
• Word Clock input
• Word Clock output

This turns the ISA One from a purely analogue front end into a highly flexible studio preamp capable of integrating directly with modern digital and Dante-based systems.

Dante Network Audio

Dante allows multichannel digital audio to be transmitted over standard Ethernet networking.

With the ADN2 installed, the ISA One can feed its converted audio directly into a compatible Dante network.

This can be particularly useful for:

• Professional recording studios
• Live recording
• Broadcast
• Education facilities
• Installed audio
• Remote recording rooms
• Networked production environments

Configuration is handled using compatible Dante and Focusrite network-control software.

What Makes The Focusrite ISA One Special?

The ISA One brings Focusrite's established ISA microphone preamplifier design into a compact desktop format.

Its microphone preamp is derived from the classic ISA 110 circuit, originally developed for Focusrite's large-format studio consoles.

The combination of a Lundahl input transformer, wide gain range and selectable input impedance makes the ISA One suitable for everything from sensitive condenser microphones to low-output dynamics and ribbons.

Unlike many single-channel preamps, it also includes a separate instrument DI path, allowing a microphone and DI signal to be handled independently.

Lundahl Transformer Mic Preamp

The microphone input uses a Lundahl input transformer, an important part of the traditional ISA signal path.

The transformer contributes to the distinctive character associated with the ISA range while retaining:

• Wide frequency response
• High headroom
• Low noise
• Strong transient reproduction
• Excellent detail

Up To 80dB Of Mic Gain

The ISA One provides up to approximately 80dB of microphone gain, combining stepped gain selection with continuous trim adjustment.

This makes it particularly useful with:

• Condenser microphones
• Dynamic microphones
• Ribbon microphones
• Low-output sources
• Quiet acoustic instruments
• Spoken word and voiceover

Selectable Microphone Input Impedance

One of the ISA One's most useful features is its selectable microphone impedance.

Different impedance settings can subtly alter the interaction between a microphone and preamp, affecting:

• Frequency response
• Transient character
• Output level
• Tonal balance

This allows the engineer to experiment with different responses from the same microphone.

Independent Instrument DI

The front-panel instrument input operates independently from the main microphone channel.

This makes it useful for recording a microphone and direct signal simultaneously.

Typical applications include:

• Bass DI alongside a miked amplifier
• Electric guitar DI for later reamping
• Acoustic pickup alongside a microphone
• Keyboard or instrument sources
• Reamping workflows

A dedicated Amp Output also allows the instrument signal to be passed onward to an amplifier.

Cue Mix & Headphone Monitoring

The ISA One incorporates a headphone monitoring section with external stereo cue inputs.

This allows performers to monitor:

• The ISA input
• A stereo backing mix
• A combination of both

It makes the unit particularly practical for overdubbing and small recording setups where a separate monitoring controller may not be available.

Insert Point

Balanced insert send and return connections allow external processors to be placed into the signal path.

Potential uses include:

• Compressor
• Equaliser
• De-esser
• Hardware channel strip processing

This provides considerably more flexibility than a basic one-box microphone preamp.

High-Pass Filter

The ISA One provides a 75Hz high-pass filter with an 18dB/octave slope.

This can help reduce:

• Low-frequency rumble
• Stand vibration
• Unwanted room noise
• Excessive proximity-effect bass
• Handling noise

Who Is It For?

Recording engineers – A versatile premium analogue front end with professional digital connectivity.

Vocal recording setups – High gain, selectable impedance and transformer character work particularly well with a wide range of microphones.

Ribbon microphone users – The substantial gain range makes it capable of handling many lower-output microphones.

Bass players – The independent DI makes it excellent for recording clean direct bass.

Dante studios – The installed ADN2 allows direct integration into networked audio systems.

Project studios – Provides a high-quality front end that can remain useful even as interfaces and computers change.

Location engineers – The hardcase and compact desktop format make it suitable for portable recording rigs.

Technical Specifications

Specification	Details
Product Type	Microphone Preamp / DI
Brand	Focusrite
Model	ISA One Analogue
Mic Preamp Type	Transformer-Based
Input Transformer	Lundahl
Mic Gain	0–60dB Stepped + Up To 20dB Trim
Maximum Available Mic Gain	Approx. 80dB
Phantom Power	48V
Phase Reverse	Yes
High-Pass Filter	75Hz, 18dB/Octave
Variable Mic Impedance	Yes
Line Input	Yes
Instrument DI	Yes
Amp Output	Yes
Insert Send / Return	Yes
Headphone Output	Yes
Cue Mix Input	Stereo
Digital Card	Focusrite ISA ADN2 Installed
Digital Resolution	Up To 24-bit / 192kHz
Dante	Primary & Secondary
AES3	Yes
S/PDIF	Coaxial
ADAT	Optical
Word Clock Input	Yes
Word Clock Output	Yes
Power Supply	Internal Universal PSU
Mains	100–240V, 50/60Hz
Dimensions	Approx. 220 × 290 × 104mm
Weight	Approx. 3.9kg
Included	Hardcase
Condition	Pre-Owned, Very Good

Analogue Connections

Front Panel

• 1/4" Instrument Input
• 1/4" Amp Output
• Headphone Output

Rear Panel

• XLR Microphone Input
• Line Input
• Main XLR Output
• DI XLR Output
• Insert Send
• Insert Return
• Stereo Cue Mix Inputs

Digital Connections – ISA ADN2

The installed expansion card provides:

• 2 x Dante Ethernet ports
• AES3 output
• RCA S/PDIF output
• Optical ADAT output
• BNC Word Clock input
• BNC Word Clock output

Digital conversion supports sample rates up to 192kHz at 24-bit resolution.

ISA One Without ADN2 vs This Example

A standard ISA One is fundamentally an analogue microphone preamp and DI.

This particular unit already has the optional digital card installed, adding:

• High-quality A/D conversion
• Dante network audio
• AES3
• S/PDIF
• ADAT
• Word Clock

Buying an ISA One with the card already fitted removes the need to source and install the optional upgrade separately.

With the Dante card valued at £379, it also adds considerable value to this particular pre-owned package.

Power Requirements

The ISA One uses an internal universal mains power supply accepting approximately:

100–240V AC, 50/60Hz

No external power supply is required.

Hardcase

A hardcase is included, providing useful additional protection during transport and storage.

This is particularly beneficial for:

• Mobile recording
• Location work
• Studio-to-studio transport
• Live production
• Keeping the ISA One and cabling protected between sessions

Fair Deal Music Verdict

★★★★★ 5/5

The Focusrite ISA One remains an extremely capable professional microphone preamp thanks to its transformer-based ISA signal path, generous gain range, selectable impedance and genuinely useful independent DI.

This particular example stands out because the ISA ADN2 Dante digital expansion card is already installed.

That upgrade, worth £379, adds up-to-24-bit/192kHz conversion together with Dante, AES3, S/PDIF, ADAT and Word Clock connectivity, considerably expanding the ISA One's potential in a modern studio.

Presented in Very Good Condition and supplied with a hardcase, this is an especially attractive option for engineers looking for the classic ISA analogue front end with contemporary networked digital connectivity already fitted.

Why Buy Pre-Owned From Fair Deal Music?

Professional studio hardware can offer excellent long-term value when bought pre-owned.

Every pre-owned item at Fair Deal Music is individually assessed, with significant upgrades and included accessories clearly represented.

On this ISA One, the installed ISA ADN2 Dante card and included hardcase are both clearly identified as part of the package.

Why Buy From Fair Deal Music?

When you buy from Fair Deal Music, you're choosing one of the UK's most established, independent family run music retailers since 1987.

When you buy from us, you benefit from:

• Family-run independent retailer established in 1987
• Birmingham's largest independent music store
• 6,000+ Trustpilot reviews
• Expert musician-led advice
• Pre-owned equipment individually assessed
• Upgrades clearly described
• Secure ordering
• Fast UK delivery
• Large Birmingham showroom
• Friendly support before and after purchase

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Contact our team for a no-obligation valuation and find out what your existing equipment could be worth towards your next purchase.

Frequently Asked Questions

What condition is this Focusrite ISA One in?

It is presented in Very Good Condition, showing some cosmetic wear consistent with careful previous studio use while remaining fully functional.

Does this ISA One have the digital option installed?

Yes. It has the Focusrite ISA ADN2 digital expansion card installed.

Does the installed card support Dante?

Yes. The ADN2 provides Dante network audio connectivity.

How much is the Dante card worth?

The installed expansion card is valued at £379.

What digital resolution does the ADN2 support?

It supports conversion at up to 24-bit / 192kHz.

What other digital outputs does the card provide?

In addition to Dante, it provides AES3, S/PDIF and ADAT outputs.

Does it have Word Clock?

Yes. The ADN2 provides both Word Clock input and output.

What type of microphone preamp does the ISA One use?

It uses Focusrite's transformer-based ISA microphone preamp, derived from the original ISA 110 design.

Does it use an input transformer?

Yes. The microphone preamp uses a Lundahl transformer.

How much microphone gain is available?

Up to approximately 80dB is available through the stepped gain and continuous trim controls.

Is phantom power available?

Yes. 48V phantom power is provided for compatible condenser microphones.

Can it be used with ribbon microphones?

Yes. Its high available gain makes it particularly useful with many passive ribbon microphones. Phantom power should only be used where appropriate for the connected microphone.

Does it have variable input impedance?

Yes. Multiple microphone impedance settings allow interaction with different microphones to be adjusted.

Does it have a DI input?

Yes. It features an independent instrument DI input.

Can the mic and DI be used at the same time?

Yes. One of the ISA One's useful features is its independent DI signal path.

Does it have an insert?

Yes. Balanced insert send and return connections allow external hardware processors to be incorporated.

Does it have headphone monitoring?

Yes. It features a headphone output and stereo cue-mix facility.

Does the ISA One require an external power supply?

No. It uses an internal universal mains supply.

Is a hardcase included?

Yes. A hardcase is included.

Is the Dante card removable?

The ISA ADN2 is an internally fitted option card designed specifically for compatible ISA products, including the ISA One.

Can I use the Dante card with Dante Controller?

Yes. Dante network configuration can be managed through compatible Dante software, while Focusrite's RedNet Control can also be used for supported configuration functions.

Can I part-exchange studio equipment against it?

Yes. Fair Deal Music considers trade-ins and part exchanges across a wide range of studio equipment, musical instruments and other gear.