How did AMG STA mono achieve better sonic characteristic, in addition to more power than AMG STA stereo ?
The standard method for bridging a stereo amp into mono employs a series of op amps (OPA) in order to invert the input signals to one of the stereo amp, thereby creating an opposite phase, which can then be combined to increase power. Conversely, the AMG STA’s innovative bridging circuit utilises a design we call Single-Ended Direct-Inject Bridge Technology, in which the mono mode, in addition to acquiring more than double the power, sounds livelier and more dynamic.
With improvements to every area, the bar has been raised for what is achievable with audio performance in small form factor.
The AMG STA has a flavor of its own, so it is hard to compare it with the Evolution One, which derives some of its design from or the similarly priced ST-10. AMG STA sounded smooth and relaxing. Detail, resolution, dynamics, and speed are in the ST-10 ballpark, yet the sound is quite different.
Drawing comparison with the Evolution One, they shared a trait of ease in reproducing the details of the recording comes afore. However, AMG STA does things differently. While the Evolution One has that inviting warmth, the AMG STA wants to allure the listener. Hence, instead of glitz and glamor, which pulls you in quickly into the performance, the AMG STA has a demeanor that slowly brings you into the music.
Tonal qualities of the AMG STA leans toward being full and rich, so instruments and vocals seem to gain extra body, weight, and harmonic richness. It may not be the most accurate reproduction but does make Jazz and Vocal pieces highly addictive. It may take away the raw edge of Rock and Electronic music and sounds less exciting for some.
The sound stage has an attractive characteristic. A linear presentation is like having floodlights shining on all the performers such that everyone can be seen equally well. The AMG STA, however, has more of a spotlighting effect, where performers are focused on getting your attention.
It is tough to put the sound of the AMG STA into measurable attributes as the presentation is quite different from the other series. You’ll need to try it and hear for yourself.
- Stereo Power: 2 X 130W @ 8 Ohm & 2 X 200W @ 4 Ohm
- Mono Power: 300W @ 8 Ohm & 320W @ 4 Ohm
- Rated / Peak Current: 10A / 15A
- Gain : 26 (stereo) & 52 (mono)
- Signal to Noise Ratio : 100 dB @ 10W
- THD+N : 0.006
- Frequency Response : 10Hz~50K Hz +-0.2dB @ 8 Ohm. 58K Hz @ -3dB
- Input Impedance: 1M Ohm
- Sensitivity: 1.2 Vrms @ Stereo; 0.95 Vrms @ Mono
Front Panel Power Switch
Power On: Up position
Power Off: Down position
If using the optional remote control, this switch should be in the Down position
Remote Control Code
CUSTOM CODE 0X06
— KEY CODE—
POWER ON / OFF 0X0
Christiaan Punter, HFA (hifi-advice.com)
The AMG-PRA + AMG-STA form a beautiful combo, not only visually, but also in terms of sonic synergy, the preamp’s robust and full sound perfectly complimenting the power amp’s slightly leaner balance. The combined result is a musically always engaging sound that is solid and full-bodied, smooth and refined yet highly detailed and transparent, with perfect pacing, and great dynamics. Honestly, at 3200 euro, I haven’t heard a better amplifier, either integrated or separates.
As great as the combo is, the AMG-STA power amplifier really is the star of the show. On its own, it is capable of performing on a level that is well and truly beyond what might be expected from an amplifier at its price point. To be more precise: if the preamp already performs at a level that belies its price sticker, the power amp steals the show as it has the ability to perform on the level of amplifiers that typically cost multiples of its modest 1.595-Euro price. I am not kidding!
Combine the AMG-STA with a great volume-controlled DAC and you’ll have a nearly unbeatable system. Between single and dual amps, if ever there was a no-brainer decision, this is it. The pair simply raises the performance in each and every audiophile parameter, without harming the emotional involvement.
As should be clear by now, I am definitely impressed by NuPrime power amplifiers. First, the ST-10 proved to be a keeper, then the ST-10 Monos proved that the concept could be taken further, then the AMG-STA proved that Class-D can be as “analog” and as refined as the best linear power amplifiers, and now, the pair of AMG-STA’s have further raised the bar. Although the ST10 and ST10 Monos still have their unique flair, as of now, the pair of AMG-STA’s are my personal reference in the field of affordable power amplifiers with true high-end aspirations.
Whether used as a single stereo model or as a double-mono pair, the AMG-HPA is an absolute HFA Favorite.
Read full review of AMG STA (Stereo) then follow by AMG STA (mono) review
Drew Kalbach, The Absolute Sound
…“Active Low Frequency and Harmonic Gain” control feature. To put it very simply, this knob is somewhat like Ye Olde Loudness switch of yore. When turned on it very noticeably boosts bass, without increasing the overall volume…It worked well with my Wharfedale 225s, and actually sounded fairly nice with my Omen Dirty Weekend on its lowest setting.
The single STA was more than enough to power my Zu Omen Dirty Weekends, and made my copy of the recent Ray Charles vinyl reissue Genius + Soul = Jazz sing and scream and shout. Lows were suitably solid, and the midrange really shone with an extremely pleasant smoothness. I never felt as though the AMG STA lagged behind or ran out of headroom powering the Zu DWs, even on this very dynamic recording.
Where this dual-mono configuration really worked was with the Polk L600s, the more difficult pair of speakers to drive. The AMG STA retained its signature relaxed and easy sound, but with that much power on tap really opened up the full potential of the Polks. The backgrounds were shockingly black, and it almost felt as if the AMG PRA preamp was nearly transparent, if you’ll forgive a reviewing cliché. That deep noise floor allowed the music to shine with a crispness and dynamism that I absolutely loved.
Williams’ fills sounded exuberant and rhythmically complex, and the system never compromised or slowed down his fascinating drumming. In the midrange, the piano and horns were smooth and silky with a hint of nice, heavy warmth down in their lower regions. Hancock’s solo was quick and slithering, like the song’s namesake, and each note was clearly delineated. Attacks and decays were on point, which added to the whole rhythmic picture building throughout the song. When the horns massed for the theme, each instrument remained wholly itself and focused, creating a wide sense of soundstage. The STA/PRA dual-mono combo worked very well with the L600s, since the speakers have a very solid and deep lower end, and the amp/preamp shines in the lower registers. It was that deep heft that really brought a difficult song like “King Cobra” to life, and leant the entire ensemble a massive sound.
For many folks, I suspect a single STA will provide enough power, but for those who have more difficult-to-drive speakers, or those who want a massive amount of power on tap and ready to go, the monoblock setup is fantastic. This is a system worth trying and comes highly recommended.
-> Read full review