Review sample provided by Dimex
Retail Price: 4.995 euro
Available in Silver or Black
With the Evolution STA, NuPrime presents an amplifier that delivers a breakthrough in distortion reduction. To achieve this, they employ a technique they call Only Distortion Cancellation (ODC). A typical feedback error correction design inverts the output signal for summation with the original input signal to derive the negative error signal, which adds to the next cycle of the input signal to form a more accurate output signal. NuPrime’s ODC Class-D design derives the error signal from MOSFET devices and the output filter circuit directly, significantly reducing the negative feedback signal, which resulted in a substantial reduction in distortion THD+N of 0.002% @1kHz(5W), and less than 0.005% THD+N at 1KHZ (2W-100W).
Highlights include a 650KHz high-speed switching frequency to allow greater resolution, the application of the high-end NJR MUSES8820 op-amp for the preamp stage, and the Class-D oscillation circuit, a 550W high-power, ultra-thin toroidal transformer power supply with a total of 52,000uF filter capacitors. The amplifier uses low resistance terminals and is able to supply a rated RMS power of 230W at 8 Ohm and 40A of current.
After having favorably reviewed the ST-10 and the AMG-STA and having concluded that they have mutually exclusive strong areas, Jason Lim of NuPrime later mentioned that they were working on a new amplifier that would combine the strong points of both amplifiers. That new amplifier is the Evolution STA. Imagine my anticipation!
My power installation consists of a Siemens Sitor Cylindric Fuse, feeding an uninterrupted run of solid-core installation wire that ends in three wall-mounted GigaWatt G-044 Schuko Wall Sockets. These wall sockets feed three Popp/Eurolite unfiltered aluminum 8-output distributors via insulated runs of the same kind of solid-core installation wire.
Prior to starting my serious listening sessions, I made sure to leave the amp powered on for several days, and even before this, the importer also used it at home for two weeks meaning that the unit should be properly run in.
For my first listening, the Evolution STA was positioned on top of the CH A1.5, connected with the stock power cable, just like the A1.5, as the only exception in my system. While this will probably not be ideal for the amplifier, it does provide the ideal setup to compare the two amplifiers. Is there any sense in comparing the NuPrime to an amp costing over four times as much? Maybe not for prospective buyers, but for me, it is. The CH remains my reference and as such, it is a logical starting point for me. Don’t worry, though, as I will also compare the Evolution STA to the very affordable NuPrime AMG-STA and ST-10.
After having listened to a varied playlist via my regular setup, I reconnected the AudioQuest Fire RCA interlinks and the Jorma Trinity speaker cables from the CH A1.5 to the Evolution STA and adjusted the CH L1 preamp -3dB to compensate for the NuPrime’s higher gain. Even though I have not forgotten how great the AMG-STA and the ST-10 are relative to their price point, still, I prepared for the sound quality to take a few steps back with the Evolution STA compared to the CH. But that’s not exactly how it went down. Rather, my first impression was one of amazement.
The Evolution STA sounds marvelously energetic, expressive, and utterly coherent with immense neutrality but without tipping over into leanness or coolness. The amp is also very linear and quite detailed but not revealing to the point of being analytical, let alone clinical. First and foremost, it paints the complete musical picture while sounding nothing like your typical Class-D amplifier.
Between the CH and the NuPrime, certain key aspects have certainly noticeably shifted, but on the surface of it, and in an absolute sense, there is not very much to indicate that we just switched from a 31 K amplifier to one costing only 5 K. Honestly, it was more like switching from one high-end amplifier to another, invoking differences catering more to taste than to absolute quality. For instance, the Big Swiss amp remains the King of resolution and refinement. But to offset this, the NuPrime actually overshadows the CH in a couple of areas. Do read on to find out precisely how the two compare!