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Universal Audio Apollo x4 Gen 2 Thunderbolt Audio Interface Essentials

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Description
Universal Audio Apollo x4 Gen 2 front panel showing monitor knob, dual Hi-Z inputs, and dual headphone outputs

129 dB of Dynamic Range in Something You Can Fit in a Carry-On

The Apollo x4 Gen 2 is what happens when Universal Audio takes the conversion architecture from their rackmount flagship line and puts it in a desktop box. The result is 129 dB of dynamic range and 24-bit/192kHz A/D and D/A conversion that sits at the same level as interfaces costing significantly more and occupying rack space you may not have. For commercial engineers who travel, boutique studio owners who need their best conversion everywhere, and producers building serious in-the-box rigs, that is a meaningful shift in what is possible from a desktop unit.

The Gen 2 update is not cosmetic. UA redesigned the D/A converters specifically for monitoring accuracy, which means what you hear coming back through your speakers and headphones is a more honest representation of the actual recording. That matters more than most engineers realize until they mix on a reference-grade front end and stop chasing phantom problems that were never in the recording to begin with. Four Unison preamps handle your mic and line inputs, with two front-panel Hi-Z instrument inputs that route through the same Unison-capable signal path for direct guitar and bass tracking.

 Apollo x4 Gen 2 top view showing monitor control section, talkback button, and input level controls

QUAD Core DSP That Lets You Track Through the Real Thing

The onboard UAD-2 QUAD Core processor is what separates this from a high-spec converter with good preamps. Every plugin running on that processor, the Neve 1073, the API Vision, the Manley Voxbox, the LA-2A, the 1176, runs at near-zero latency directly from the hardware without touching your CPU. Tracking vocals through a real Neve 1073 emulation with the impedance, gain staging, and circuit behavior actually changing based on the model is not the same as doing it in post. You hear it while performing. The performance changes. The takes change.

The Unison technology is how UA accomplishes this. When you load a Unison preamp model, the Apollo physically adjusts input impedance and gain structure to match the original hardware's interaction with your microphone. A ribbon mic running into a Neve model behaves differently than it does running into a clean preamp, because the Apollo is changing the electrical relationship between the mic and the circuit in real time. For producers who track through hardware in commercial rooms and want that same experience at their desk, this is as close as software gets to the physical thing. Auto-Gain handles input calibration across all four channels in seconds when you need to move fast.

 Universal Audio Apollo x4 Gen 2 rear panel with 4 XLR combo inputs, monitor outs, line outs, and Thunderbolt 3 port

ADAT Expansion, Sonarworks Correction, and Room to Grow

The optical Toslink I/O handles ADAT or S/PDIF, which means you can add an 8-channel preamp like the UA 4-710d and bring eight additional inputs into the Apollo without additional conversion hardware. Or run a word clock-locked outboard converter for mastering-grade line-level work through the existing D/A stage. The I/O counts as 12 inputs and 18 outputs at the interface level, and if the project outgrows the desk, you can chain up to four Thunderbolt Apollo interfaces for up to 128 channels of premium I/O, all managed from the x4 as the control hub.

The monitor controller section is fully featured: alternate speaker switching, integrated talkback, Bass Management for subwoofer integration, and Apollo Monitor Correction powered by Sonarworks, which runs on a dedicated DSP core using over 20 precision filters and up to 100ms of loudspeaker time alignment. Two headphone outputs each with independent level controls let you run a cue mix for a vocalist and a reference mix for yourself at the same time. Plug-In Scenes recall your complete UAD Console state over MIDI, which matters for engineers who switch between tracking and mixing setups mid-session or run the same project across multiple rooms. The Essentials+ bundle includes 36 UAD plugins out of the box, with the full library of over 200 available to unlock.

Highlights

  • 12x18 Thunderbolt 3 desktop audio interface, 24-bit/192kHz A/D and D/A conversion
  • 129 dB dynamic range, lowest distortion of any Apollo desktop to date
  • 4 Unison mic/line preamps with physical impedance and gain staging adjustment per model loaded
  • 2 front-panel Hi-Z instrument inputs routing through Unison-capable signal path
  • UAD-2 QUAD Core onboard DSP for near-zero latency UAD plugin processing
  • Over 200 UAD plugins available including Neve 1073, API Vision, Manley Voxbox, LA-2A, 1176, Pultec
  • Hybrid workflow: combine QUAD Core DSP with native CPU processing for large sessions
  • Auto-Gain: one-click input calibration across all channels during a short training window
  • Plug-In Scenes: recall complete UAD Console states via MIDI for fast session switching
  • Apollo Monitor Correction powered by Sonarworks: runs on dedicated DSP, 20+ precision filters, up to 100ms time alignment
  • Bass Management for subwoofer integration in stereo monitoring configurations
  • Fully featured monitor controller: alternate speaker switching, integrated talkback mic
  • 2x 1/4" TRS headphone outputs with independent level controls
  • Optical Toslink I/O: ADAT (up to 8 channels) or S/PDIF
  • Expandable: chain up to 4 Thunderbolt Apollo interfaces for up to 128 channels of I/O
  • Analog outputs: 2x 1/4" monitor, 4x 1/4" line out (ALT 1/2)
  • Compatible with LUNA, Logic Pro, Pro Tools, Cubase, Ableton Live, and all major DAWs via VST, AU, AAX 64
  • Mac: macOS 10.15 or later, Quad Core i7 or higher
  • PC: Windows 10 Anniversary update or later, Quad Core i7 or higher
  • Includes UA Essentials+ Plug-in Suite (36 plugins), 12V DC external power supply

Apollo x4 Gen 2 Specifications

Specification Details
Type Desktop Thunderbolt 3 audio interface with onboard DSP
Simultaneous I/O 12 in / 18 out
A/D Resolution 24-bit / 192kHz
Dynamic Range 129 dB
DSP UAD-2 QUAD Core processor
Preamps 4x Unison-enabled mic/line (XLR/TRS combo)
Hi-Z Inputs 2x front panel (replaces channels 1 and 2 when engaged)
Phantom Power 48V
Analog Inputs 4x XLR/1/4" combo (mic/line), 2x 1/4" Hi-Z
Analog Outputs 2x 1/4" TRS (monitor), 4x 1/4" TRS (line out / ALT 1-2)
Headphone Outputs 2x 1/4" TRS with independent level controls
Digital I/O 1x Optical Toslink in, 1x Optical Toslink out (ADAT or S/PDIF)
Computer Connectivity 1x USB-C Thunderbolt 3 (cable sold separately)
Expansion Up to 4 Thunderbolt Apollo interfaces, up to 128 channels total
Monitor Controller Alternate speaker switching, integrated talkback mic, Bass Management
Room Correction Apollo Monitor Correction by Sonarworks (runs on dedicated DSP core)
Software UA Essentials+ Plug-in Suite (36 UAD plugins included)
DAW Compatibility LUNA, Logic Pro, Pro Tools, Cubase, Ableton Live, and others via VST, AU, AAX 64
OS Requirements (Mac) macOS 10.15 or later, Quad Core i7 or higher
OS Requirements (PC) Windows 10 Anniversary update or later, Quad Core i7 or higher
Power Supply 12V DC external (included, with regional adapters)
Form Factor Desktop
Part Number APX4G2-ESS

What's in the Box

Included Items
Universal Audio Apollo x4 Gen 2 Interface
12V DC External Power Supply with Regional Adapters
UA Essentials+ Plug-in Suite License
Quick-Start Guide and Documentation

Thunderbolt 3 cable sold separately. macOS 10.15 or later required (Quad Core i7 or higher). Windows 10 Anniversary update or later required (Quad Core i7 or higher). Apollo Monitor Correction by Sonarworks delivered via software update.

Shipping

Shipping & Returns

  • We deliver all US orders in 3–5 business days
  • Free cancellations
  • Returns accepted within 30 days (unused items)

Order Confirmation

Once your order is placed, you will receive an order confirmation email. This confirms that we have received your order and have pre-authorized your credit card for the purchase. After confirming availability with our suppliers, we will proceed accordingly:

  • If your item is available and ready to ship within 1–2 business days, we will process the charge and arrange for shipment.

  • If your item is on backorder or unavailable, the pre-authorization will be voided and you will be notified by email.

  • Please note: While most items ship out within 1–2 business days, total delivery time is typically 3–5 business days, depending on your location and carrier handling.

Order Shipment

If your item is in stock and your payment has been processed, your order will typically ship within 1–2 business days. Total delivery time is approximately 3–5 business days from the date of order. Once shipped, you will receive tracking information at the email address provided during checkout within 24 hours of dispatch.

If you have not received tracking information within 3–5 business days of placing your order, please contact us at support@proaudioreserve.com.

The Distributor-Direct Advantage

To ensure you receive the most recent hardware revisions and 100% factory-sealed units, Pro Audio Reserve utilizes a Distributor-Direct fulfillment model. Unlike big-box retailers that may ship "floor models" or gear that has been sitting in general-purpose warehouses, your equipment is pulled directly from the primary manufacturer hub, serialized, and dispatched. This process ensures the highest level of quality control for professional-grade recording equipment.

Shipping Policy

We currently offer free shipping within the United States only. If the checkout process on our website allows you to enter a shipping address and complete your order, your location is eligible to receive delivery.

Changing Shipping Address

If you need to change your shipping address after your order has been processed or shipped, we will do our best to accommodate the request. Please note that address changes may result in delivery delays. Any additional costs incurred due to address changes, including carrier fees or rerouting charges will be the responsibility of the customer. No exceptions.

Shipping Times

All shipping times provided are estimates and should not be considered guarantees. Most orders ship out within 1–2 business days from the time payment is processed. However, total delivery time is typically 3–5 business days, depending on your location, carrier performance, and supplier fulfillment timelines.

We work closely with our vendors to ensure timely deliveries, but please note that supply chain disruptions, high-demand periods, or weather events may occasionally cause delays beyond our control.

  • To avoid misunderstandings: The “shipping time” refers to the total time from order placement to final delivery, not just when the item leaves the warehouse.

  • Cancellations: If you choose to cancel your order because it has not arrived within the estimated delivery window, you may be responsible for applicable shipping charges, restocking fees, warehouse handling costs, and other related fees.

  • Chargebacks: Customers who initiate chargebacks due to shipping delays without contacting us first may be held legally responsible for losses. We strongly encourage open communication so we can resolve any delivery concerns directly and efficiently via our Atlanta-based support team.

Delivery Options

  • Threshold Shipping: Your item will be delivered to your front door, porch, garage, or a covered entryway.

 

Why Buy From Us

We get it. You've got a lot of choice when it comes to online retailers.
Here's why we think you should shop with us at ProAudioReserve.

  • Free Shipping USA wide. 
  • 30 Day Easy Returns. Not happy with your product, we'll take it back noquestions asked.
  • Great Service. We pride ourselves on the best service, anywhere.

Reviews

Customer Reviews

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Description
Universal Audio Apollo x4 Gen 2 front panel showing monitor knob, dual Hi-Z inputs, and dual headphone outputs

129 dB of Dynamic Range in Something You Can Fit in a Carry-On

The Apollo x4 Gen 2 is what happens when Universal Audio takes the conversion architecture from their rackmount flagship line and puts it in a desktop box. The result is 129 dB of dynamic range and 24-bit/192kHz A/D and D/A conversion that sits at the same level as interfaces costing significantly more and occupying rack space you may not have. For commercial engineers who travel, boutique studio owners who need their best conversion everywhere, and producers building serious in-the-box rigs, that is a meaningful shift in what is possible from a desktop unit.

The Gen 2 update is not cosmetic. UA redesigned the D/A converters specifically for monitoring accuracy, which means what you hear coming back through your speakers and headphones is a more honest representation of the actual recording. That matters more than most engineers realize until they mix on a reference-grade front end and stop chasing phantom problems that were never in the recording to begin with. Four Unison preamps handle your mic and line inputs, with two front-panel Hi-Z instrument inputs that route through the same Unison-capable signal path for direct guitar and bass tracking.

 Apollo x4 Gen 2 top view showing monitor control section, talkback button, and input level controls

QUAD Core DSP That Lets You Track Through the Real Thing

The onboard UAD-2 QUAD Core processor is what separates this from a high-spec converter with good preamps. Every plugin running on that processor, the Neve 1073, the API Vision, the Manley Voxbox, the LA-2A, the 1176, runs at near-zero latency directly from the hardware without touching your CPU. Tracking vocals through a real Neve 1073 emulation with the impedance, gain staging, and circuit behavior actually changing based on the model is not the same as doing it in post. You hear it while performing. The performance changes. The takes change.

The Unison technology is how UA accomplishes this. When you load a Unison preamp model, the Apollo physically adjusts input impedance and gain structure to match the original hardware's interaction with your microphone. A ribbon mic running into a Neve model behaves differently than it does running into a clean preamp, because the Apollo is changing the electrical relationship between the mic and the circuit in real time. For producers who track through hardware in commercial rooms and want that same experience at their desk, this is as close as software gets to the physical thing. Auto-Gain handles input calibration across all four channels in seconds when you need to move fast.

 Universal Audio Apollo x4 Gen 2 rear panel with 4 XLR combo inputs, monitor outs, line outs, and Thunderbolt 3 port

ADAT Expansion, Sonarworks Correction, and Room to Grow

The optical Toslink I/O handles ADAT or S/PDIF, which means you can add an 8-channel preamp like the UA 4-710d and bring eight additional inputs into the Apollo without additional conversion hardware. Or run a word clock-locked outboard converter for mastering-grade line-level work through the existing D/A stage. The I/O counts as 12 inputs and 18 outputs at the interface level, and if the project outgrows the desk, you can chain up to four Thunderbolt Apollo interfaces for up to 128 channels of premium I/O, all managed from the x4 as the control hub.

The monitor controller section is fully featured: alternate speaker switching, integrated talkback, Bass Management for subwoofer integration, and Apollo Monitor Correction powered by Sonarworks, which runs on a dedicated DSP core using over 20 precision filters and up to 100ms of loudspeaker time alignment. Two headphone outputs each with independent level controls let you run a cue mix for a vocalist and a reference mix for yourself at the same time. Plug-In Scenes recall your complete UAD Console state over MIDI, which matters for engineers who switch between tracking and mixing setups mid-session or run the same project across multiple rooms. The Essentials+ bundle includes 36 UAD plugins out of the box, with the full library of over 200 available to unlock.

Highlights

  • 12x18 Thunderbolt 3 desktop audio interface, 24-bit/192kHz A/D and D/A conversion
  • 129 dB dynamic range, lowest distortion of any Apollo desktop to date
  • 4 Unison mic/line preamps with physical impedance and gain staging adjustment per model loaded
  • 2 front-panel Hi-Z instrument inputs routing through Unison-capable signal path
  • UAD-2 QUAD Core onboard DSP for near-zero latency UAD plugin processing
  • Over 200 UAD plugins available including Neve 1073, API Vision, Manley Voxbox, LA-2A, 1176, Pultec
  • Hybrid workflow: combine QUAD Core DSP with native CPU processing for large sessions
  • Auto-Gain: one-click input calibration across all channels during a short training window
  • Plug-In Scenes: recall complete UAD Console states via MIDI for fast session switching
  • Apollo Monitor Correction powered by Sonarworks: runs on dedicated DSP, 20+ precision filters, up to 100ms time alignment
  • Bass Management for subwoofer integration in stereo monitoring configurations
  • Fully featured monitor controller: alternate speaker switching, integrated talkback mic
  • 2x 1/4" TRS headphone outputs with independent level controls
  • Optical Toslink I/O: ADAT (up to 8 channels) or S/PDIF
  • Expandable: chain up to 4 Thunderbolt Apollo interfaces for up to 128 channels of I/O
  • Analog outputs: 2x 1/4" monitor, 4x 1/4" line out (ALT 1/2)
  • Compatible with LUNA, Logic Pro, Pro Tools, Cubase, Ableton Live, and all major DAWs via VST, AU, AAX 64
  • Mac: macOS 10.15 or later, Quad Core i7 or higher
  • PC: Windows 10 Anniversary update or later, Quad Core i7 or higher
  • Includes UA Essentials+ Plug-in Suite (36 plugins), 12V DC external power supply

Apollo x4 Gen 2 Specifications

Specification Details
Type Desktop Thunderbolt 3 audio interface with onboard DSP
Simultaneous I/O 12 in / 18 out
A/D Resolution 24-bit / 192kHz
Dynamic Range 129 dB
DSP UAD-2 QUAD Core processor
Preamps 4x Unison-enabled mic/line (XLR/TRS combo)
Hi-Z Inputs 2x front panel (replaces channels 1 and 2 when engaged)
Phantom Power 48V
Analog Inputs 4x XLR/1/4" combo (mic/line), 2x 1/4" Hi-Z
Analog Outputs 2x 1/4" TRS (monitor), 4x 1/4" TRS (line out / ALT 1-2)
Headphone Outputs 2x 1/4" TRS with independent level controls
Digital I/O 1x Optical Toslink in, 1x Optical Toslink out (ADAT or S/PDIF)
Computer Connectivity 1x USB-C Thunderbolt 3 (cable sold separately)
Expansion Up to 4 Thunderbolt Apollo interfaces, up to 128 channels total
Monitor Controller Alternate speaker switching, integrated talkback mic, Bass Management
Room Correction Apollo Monitor Correction by Sonarworks (runs on dedicated DSP core)
Software UA Essentials+ Plug-in Suite (36 UAD plugins included)
DAW Compatibility LUNA, Logic Pro, Pro Tools, Cubase, Ableton Live, and others via VST, AU, AAX 64
OS Requirements (Mac) macOS 10.15 or later, Quad Core i7 or higher
OS Requirements (PC) Windows 10 Anniversary update or later, Quad Core i7 or higher
Power Supply 12V DC external (included, with regional adapters)
Form Factor Desktop
Part Number APX4G2-ESS

What's in the Box

Included Items
Universal Audio Apollo x4 Gen 2 Interface
12V DC External Power Supply with Regional Adapters
UA Essentials+ Plug-in Suite License
Quick-Start Guide and Documentation

Thunderbolt 3 cable sold separately. macOS 10.15 or later required (Quad Core i7 or higher). Windows 10 Anniversary update or later required (Quad Core i7 or higher). Apollo Monitor Correction by Sonarworks delivered via software update.

Shipping

Shipping & Returns

  • We deliver all US orders in 3–5 business days
  • Free cancellations
  • Returns accepted within 30 days (unused items)

Order Confirmation

Once your order is placed, you will receive an order confirmation email. This confirms that we have received your order and have pre-authorized your credit card for the purchase. After confirming availability with our suppliers, we will proceed accordingly:

  • If your item is available and ready to ship within 1–2 business days, we will process the charge and arrange for shipment.

  • If your item is on backorder or unavailable, the pre-authorization will be voided and you will be notified by email.

  • Please note: While most items ship out within 1–2 business days, total delivery time is typically 3–5 business days, depending on your location and carrier handling.

Order Shipment

If your item is in stock and your payment has been processed, your order will typically ship within 1–2 business days. Total delivery time is approximately 3–5 business days from the date of order. Once shipped, you will receive tracking information at the email address provided during checkout within 24 hours of dispatch.

If you have not received tracking information within 3–5 business days of placing your order, please contact us at support@proaudioreserve.com.

The Distributor-Direct Advantage

To ensure you receive the most recent hardware revisions and 100% factory-sealed units, Pro Audio Reserve utilizes a Distributor-Direct fulfillment model. Unlike big-box retailers that may ship "floor models" or gear that has been sitting in general-purpose warehouses, your equipment is pulled directly from the primary manufacturer hub, serialized, and dispatched. This process ensures the highest level of quality control for professional-grade recording equipment.

Shipping Policy

We currently offer free shipping within the United States only. If the checkout process on our website allows you to enter a shipping address and complete your order, your location is eligible to receive delivery.

Changing Shipping Address

If you need to change your shipping address after your order has been processed or shipped, we will do our best to accommodate the request. Please note that address changes may result in delivery delays. Any additional costs incurred due to address changes, including carrier fees or rerouting charges will be the responsibility of the customer. No exceptions.

Shipping Times

All shipping times provided are estimates and should not be considered guarantees. Most orders ship out within 1–2 business days from the time payment is processed. However, total delivery time is typically 3–5 business days, depending on your location, carrier performance, and supplier fulfillment timelines.

We work closely with our vendors to ensure timely deliveries, but please note that supply chain disruptions, high-demand periods, or weather events may occasionally cause delays beyond our control.

  • To avoid misunderstandings: The “shipping time” refers to the total time from order placement to final delivery, not just when the item leaves the warehouse.

  • Cancellations: If you choose to cancel your order because it has not arrived within the estimated delivery window, you may be responsible for applicable shipping charges, restocking fees, warehouse handling costs, and other related fees.

  • Chargebacks: Customers who initiate chargebacks due to shipping delays without contacting us first may be held legally responsible for losses. We strongly encourage open communication so we can resolve any delivery concerns directly and efficiently via our Atlanta-based support team.

Delivery Options

  • Threshold Shipping: Your item will be delivered to your front door, porch, garage, or a covered entryway.

 

Why Buy From Us

We get it. You've got a lot of choice when it comes to online retailers.
Here's why we think you should shop with us at ProAudioReserve.

  • Free Shipping USA wide. 
  • 30 Day Easy Returns. Not happy with your product, we'll take it back noquestions asked.
  • Great Service. We pride ourselves on the best service, anywhere.

Reviews

Customer Reviews

Be the first to write a review
0%
(0)
0%
(0)
0%
(0)
0%
(0)
0%
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