NuPrime STA-9X Power Amplifier - Black

The STA-9, Rebuilt Around Current

The STA-9X is what the STA-9 became. Same footprint, same Class A+D idea, but the output stage has been rebuilt and the current drive is where all the engineering effort went.

It makes 130 watts per channel in stereo and 330 bridged to mono, with peaks of 170 and 370 watts. NuPrime rates its output current drive at 130% of the STA-9's, which is what matters when a speaker's impedance dips.

The input stage is a single-ended non-negative-feedback Class A design taken from NuPrime's AMG STA, the company's statement amplifier. That is where the extra resolution over the older model is supposed to come from.

Inside the Chassis

Distortion drops fourfold against the STA-9. THD+N measures 0.005% in both stereo and mono, where the older amplifier managed 0.02% and 0.01% respectively. Signal-to-noise stays better than 90dB at 1, 10 and 100 watts.

Frequency response runs 10Hz to 50kHz. Input impedance is 47k ohms across both the balanced XLR and the unbalanced RCA inputs, and gain is a single 29.10dB rather than the STA-9's two figures.

A 12V trigger input is fitted, so the amplifier wakes with the rest of the system instead of needing its own switch. It measures 235mm wide, 281 deep and 55 high, weighs 4kg, and comes in black or silver.

Who Is This Amplifier Best For?

• Your speakers dip in impedance — 130% of the STA-9's output current drive is the specification that matters when a speaker's load gets hard, and it is where this model's money went.
• You want the quieter amplifier — THD+N of 0.005% is four times better than the STA-9 measures, in both stereo and bridged mono operation.
• Your system may grow — bridged to mono the STA-9X makes 330 watts, so a second unit turns today's stereo amp into a monoblock pair.
• The rack switches on together — a 12V trigger input is fitted, so the amplifier follows your preamplifier rather than needing its own switch.
• You want the controls in their own chassis — volume and inputs come from PRA-9X or from a streamer/DAC preamp

How Does It Connect to Your System?

Connect your preamplifier by balanced XLR or unbalanced RCA, and speakers to the binding posts. For mono, set bridged mode on each amplifier before connecting anything.

Wire the 12V trigger from your preamplifier if you want the amplifier to wake and sleep with the rest of the system automatically.

Pairs Well With

Here are some great companions:

• Preamplifier: Required, and the natural next decision — see our Preamplifiers.
• Speaker Cables: Carry the current properly — see our Speaker Cables.
• Interconnects: Balanced XLR is the better run from preamp to amp — see our Interconnect Cables.
• Audio Rack: Give the amplifier a proper shelf — see our Audio Racks.

Frequently Asked Questions

How much power does it make?

130 watts per channel in stereo and 330 watts bridged to mono, with peaks of 170 and 370 watts respectively.

How is it different from the STA-9?

More output current drive, rated by NuPrime at 130% of the STA-9's, a lower THD+N figure of 0.005%, and an input stage derived from the AMG STA.

Can I use two as monoblocks?

Yes. Each bridges to 330 watts of mono output.

Does it take balanced inputs?

Yes. One balanced XLR pair and one unbalanced RCA pair, at 47k ohms, plus a 12V trigger input.

How big is it?

235mm wide, 281mm deep and 55mm high, weighing 4kg, in black or silver.

What warranty does it carry?

NuPrime covers the STA-9X with a 1-year warranty.

See It in Action

Hans Beekhuyzen pairs the STA-9X with NuPrime's DAC-9X:

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