Nuprime STA-9X black

The NuPrime STA-9X combines Class A preamplification technology with a Class D power stage to deliver 2 × 130 watts into 8 ohms (or 330 watts in mono configuration). This hybrid ULCAM (Ultra Linear Class A Module) architecture relies on a 750 kHz switching frequency—the highest on the market—and an optimized even-order harmonic circuit to reproduce the warmth of tube amplifiers without their drawbacks.

A Refined Technical Design Inspired by High-End Models

The STA-9X represents a major evolution from the STA-9 model. NuPrime has incorporated design principles from its reference amplifier, the AMG STA, notably a preamplification circuit without negative feedback coupled with a dual-feedback Class D power stage. This architecture achieves a natural sound signature while maintaining the precision of digital amplification.

The linear power supply features a high-efficiency toroidal transformer specifically designed to reduce high-frequency noise and enhance bass performance. The output current capacity, increased by 130% compared to the STA-9, allows effortless driving of low-impedance speakers with greater dynamics on complex passages.

Minimalist Design Serving Performance

Despite its power, the STA-9X remains compact: 235 × 281 × 60 mm and 4 kg. The anodized aluminum chassis ensures mechanical rigidity and effective heat dissipation. NuPrime’s proprietary isolation feet absorb unwanted vibrations.

Connectivity includes two selectable inputs (RCA and XLR) via a switch, gold-plated binding posts that accept large-gauge cables and banana plugs, as well as a 12V trigger system for integration into automated setups—a feature absent from the original STA-9.

Substantial Improvements Over the STA-9

The switching frequency increases from 550 to 750 kHz, enabling more precise reproduction of micro-details with an extended frequency response up to 50 kHz. Power output rises to 130 watts (stereo) and 330 watts (mono), while the enhanced current supply provides better control over demanding speakers.

The new preamplification circuit inspired by the AMG STA delivers higher resolution and more precise soundstage. Even-order harmonics have been finely tuned for that characteristic tube warmth, without excessive coloration. Short-circuit protection has been reinforced, and the amplifier now tolerates no-load operation.

Remarkable Versatility

The STA-9X offers appreciable installation flexibility: stereo mode for a traditional setup or mono configuration to create a bi-amplified system with two units. The 47 kΩ input impedance ensures compatibility with all preamplifiers, while the ×28.5 gain adapts to modern source levels.

Technical Specifications

Power

• 2 × 130 W / 1 × 330 W at 8 Ω
• Maximum output power: 2 × 170 W / 1 × 370 W (at 8 ohms)

Technical Specifications

• Class A + D
• Optimized even-order harmonic circuits (H2)
• Enhanced short-circuit protection
• Output current capacity 130% higher than the STA-9 model
• Switching frequency: 750 kHz
• New linear power supply with toroidal transformer

Audio Performance

• Input impedance: 47 kΩ
• Gain: × 28.5
• Signal-to-noise ratio: > 90 dB at 1 W, 10 W, 100 W
• THD+N: 0.005% (stereo), 0.005% (mono)
• Frequency response: 10 Hz - 50 kHz

Connectivity

• 1 RCA input (unbalanced)
• 1 XLR input (balanced)
• 1 trigger input and output (12 V)
• 1 stereo speaker output
• 1 mono speaker output

Physical Characteristics

• Dimensions (W × D × H): 235 × 281 × 60 mm (including feet)
• Weight: 4 kg