Enjoy high-resolution audio across multiple zones with support for over 20 streaming services, allowing seamless playback in up to 64 zones through BluOS technology.

The integrated Rapture DAC ensures superior sound quality by converting digital signals into pristine analogue audio, offering an immersive and detailed listening experience.

Featuring dual mono amplification, the Caspian 4G provides powerful and dynamic audio with minimal distortion, delivering 105W per channel at 8 ohms for exceptional performance.

Advanced connectivity options with support for HDMI eARC, Bluetooth aptX, AirPlay 2, balanced XLR inputs, and a moving magnet phono stage, the amplifier caters to both modern digital and classic analogue audio sources.

Manage your system with ease through the MaestroUnite app, which allows for seamless setup, firmware updates, and customization of audio preferences.

Crafted from machined aluminium, the Caspian 4G combines robust construction with aesthetic appeal. The included ergonomic remote control and dynamic on-unit controls enhance usability, making it ideal for both audiophiles and casual listeners.

Specifications

Analogue Inputs
• 2 × RCA Stereo (A1, A2)
• 1 × Balanced XLR (A3)

Digital Inputs
• 2 × Coax (D1, D2)
• 2 × Optical (D3, D4)
• Bluetooth Audio
• BluOS
• HDMI eARC (2.0)

Analogue Outputs
• 1 × Balanced XLR (Pre1)
• 1 × RCA Stereo (Pre2)
• 1 × RCA Stereo (Pre3)

Amplifier Output
• 1 × Pair of Speaker Binding Posts (L&R)

Other Inputs / Outputs
• Gigabit Ethernet RJ45
• Wi-Fi 5, Wi-Fi 4
• Bluetooth Low Energy (BLE)
• 12V Trigger
• Wired IR
Power: IEC C14, Fused 6.2AT

User Interface

Primary Interface (on unit)
• Dynamic Control Dial with haptic feedback (volume, input, power)

Secondary Interface (on unit)
• Backward, Play/Pause, Forward

Remote Control
• 15-button IR remote
• Black, bead-blasted & anodised aluminium body with laser-etched logo

Power Amplifier Section

Amplifier Technology: Dual Mono Euphoria Amplifier
Amplifier Class: AB

Output Power
• 105W into 8Ω (235VAC @ 1% THD, both channels driven)
• 200W into 4Ω (235VAC @ 1% THD, both channels driven)

Measurements
• THD+N (1W @1 kHz): <0.007%
• Gain: 29 dB
• Signal-to-Noise (1W/8Ω, 2Vrms A1): >85 dB
• Gain Matching: <0.5 dB
• Frequency Linearity (20 Hz–20 kHz): ±0.25 dB
• Power Supply: 600VA / 36,400 µF per rail

Phono Stage

Inputs: MM & MC

MM Section
• Gain: 53 dB
• Gain Adjustment: Low (-6 dB), Mid (0 dB), High (+6 dB)
• Input Impedance: 47kΩ / 100 pF

MC Section
• Gain: 73 dB
• Gain Adjustment: Low (-6 dB), Mid (0 dB), High (+6 dB)
• Input Impedance: 100Ω / 470 pF

RIAA Accuracy (MM/MC): ±0.3 dB (20 Hz – 20 kHz)

Rapture DAC

DAC Technology: Rapture DAC, Dual Mono Balanced
Format Support: PCM
Sampling Rate: Up to 24-bit / 192 kHz

Pre-Amplifier Section (Amp, Pre1, Pre2)

Volume Control Technology: Hybrid Digital–Analogue
Volume Control Matching: <0.25 dB
THD+N (3.9Vrms, A-Weighted): <0.0008%
SNR (3.9Vrms, A-Weighted): >108 dB
Max Output Level: 3.9 Vrms
Supported Features:
• Pre-Output
• Fixed Line-Level Output
• Subwoofer Output (Low-Pass Filtered)
• Intelligent DSP

Pre-Amplifier Section (Pre3)

Volume Control Technology: Digital
Volume Control Matching: <0.25 dB
THD+N (3.9Vrms, A-Weighted): <0.003%
SNR (3.9Vrms, A-Weighted): >108 dB
Maximum Output Level: 3.9 Vrms

Bluetooth

Protocol: A2DP Audio Profile
Codecs: SBC, aptX, AAC
Range: >15 m

Digital Inputs

Coax (D1, D2): Up to 24-bit / 192 kHz (Stereo)
Optical (D3, D4): Up to 24-bit / 192 kHz (Stereo)
HDMI ARC/eARC: Yes (2.0)

Analogue Inputs

Maximum Input Level: 6.7 Vrms
Music Sense: A2 Input
AV Mode: A2 Input

BluOS Streaming Section

BluOS Supported: Yes

Audio Formats
MP3, AAC, WMA, OGG, WMA-L, ALAC, OPUS

Hi-Res Audio
MQA, FLAC, WAV, AIFF
Supports converted DSD playback (desktop app only)

Sampling Rate: Up to 192 kHz
Bit Depth: 16–24 bit

Network Connectivity
Gigabit Ethernet RJ45
Wi-Fi 5

File Storage Protocol
SMB (Server Message Block)

USB
1 × Type-A (FAT32/NTFS, USB memory/peripherals)

Supported OS
Windows XP → current Windows
macOS (all supported versions)

Mobile App
BluOS Controller App for:
• iOS
• Android
• Kindle Fire
• Windows/macOS desktop

Music Services
20+ integrated services (Spotify, Tidal, Qobuz etc.)

Third-Party Certified Services
• Apple AirPlay
• Spotify Connect
• TIDAL Connect

Control Integrations
Creston, Control4 (OS3/OS2), RTI, URC, Lutron, NICE, GIRA, BluOS CI API, BluOS Integration Utility

MaestroUnite

Supported: Yes
Connectivity: Bluetooth LE, Wi-Fi 4 (OTA updates only)
Mobile App: iOS & Android
OTA Updates: Yes (automatic or manual)

Other

Wired IR Input: 5–14V, 3.5 mm mono
12V Trigger Input: 5–14V (On/Standby)
12V Trigger Passthrough: 3.5 mm (pass-through)

Mains Voltage
Auto-select 100–120 VAC & 220–240 VAC

Power Consumption
• Max: 610 VA
• Standby: 0.5 W
• Network Standby: 2 W (Standby Plus – fast boot)

Mechanical

Finishes: Silver, Black
Construction: Extruded & machined aluminium chassis, aluminium heatsinks
Dimensions (H×W×D): 93 × 432 × 378 mm
Weight: 15.5 kg
Sold As: Single unit