Listening
As mentioned in the original AMG STA review, it addressed all of the ST-10’s weaker areas while raising the overall quality to such an extent that it comfortably positioned itself among high-end competitors that cost multiples. But in the process, it also gave up a good portion of the ST-10’s bass heft and overall robustness. As a result, we had two amplifiers by the same brand on opposing ends: the exceptionally robust, full-bodied ST-10 and the exceptionally agile, airy, and refined AMG STA.
The first question on my mind was: Could the new model hold the ideal mid-position? Well, upon first powering up the new amp, that question was immediately answered.
Even cold from the box, the AMG STA-SE sounds remarkably full-bodied. Whereas the original AMG STA sounded relatively lean, coming from the CH A1.5, the Special Edition model manages to sound easily as solid and full-bodied. Something else I noticed right away was the little amplifier’s very deep soundstage. Many Class-D amplifiers struggle with this and sound relatively flat, but not the AMG STA-SE. Only two minutes into the first listening session, I can already confirm the manufacturer was not just speaking metaphorically when mentioning having bridged the gap between the two extremes.
How’s that for a great start?!
So far, so good, but I also noticed that the new amp was not quite as airy as the original. True, the original was extra airy, and this aspect was further emphasized by its leaner bass and lower midrange. Still, with the CH A1.5 as an unchanged reference, I could confirm that the Special Edition version sounds slightly darker, much like the ST-10. So, again, this was a confirmation that the two ranges have successfully been brought closer together.
As the amp matured over the next few days and seemed to have stabilized, it became more and more convincing, losing its initial synthetic signature and becoming timbrally ever more realistic. The AMG STA-SE is definitely full-blooded but also fast and dynamically eager. More importantly, perhaps, it is fun! This feature can easily be thrown out with the bathwater if an amplifier has so much control that it becomes overly steadfast, immovable, and uninvolving. The AMG STA-SE does not fall into this trap and walks the fine line between maintaining control and stability on the one hand and providing emotional involvement on the other. This is one of NuPrime’s most alluring qualities: their Class-D products do not sound like other Class-D products.
I mentioned further up in this review that the original AMG STA reminded me of certain classic Class-A/B Jeff Rowland amplifiers. For those who don’t know the brand, these solid-state amplifiers were famous for their supreme delicacy and refinement, mostly unheard of in traditional solid-state amplifiers until then, especially big and powerful ones that could drive Apogee loudspeakers. The AMG STA-SE is a different animal. Given its ballsy and confident yet liquid presentation, it’s perhaps more like Class A than Class A/B. More specifically, no longer Jeff Rowland-esque, in some ways, it now sounds more like a Pass Labs amplifier.
Although the amp is lively and expressive, it is far from edgy and certainly not brash unless this is in the recording. This amp may sound harmonically rich, but it is no beautifier. If a recording is so-so, it will sound as such.
Moving on to other aspects of its performance, now that the amp had been running for a week, I noted excellent bass articulation, very good resolution, and great refinement while retaining body, substance, and saturation. In strict audiophile terms, the AMG STA-SE performs admirably, certainly at its price point, but not entirely neutrally. Like the ST-10, it remains a little voluptuous and appears slightly dark. But there’s a lot to say for this balance, and I think many will prefer it to the diametrical alternative of being lean, flat, and devoid of color. Most significantly, what it does better than other Class D amplifiers I heard, including those made by NuPrime, is to sound “natural”.
Particularly, the AMG STA-SE possesses an aspect that will appeal to fans of tube equipment. Please don’t get me wrong-it’s not that this amplifier actually sounds like a tube amplifier. How could it? Transistor designs are inherently different from tube designs. The latter undeniably possess certain very special qualities as well as certain theoretically less-than-ideal side-effects. The trouble is that it is very hard, if not outright impossible, to truly get a transistor design to behave precisely like a tube design. When this is attempted, it often sounds like only the flaws of a tube design have been copied into a transistor design, leading to the worst of both worlds rather than the best. This is not the case with the AMG STA-SE. So, what am I talking about?
I am referring to an absence of whiteness with the AMG STA-SE. Just as fans of transistor designs will likely not appreciate excessive tube roundness or bloom, fans of tube designs, especially those without printed circuit boards, will likely find many transistor designs to sound lean, flat, or indeed, white. What is this whiteness, you ask? It describes a lack of body, tonality, and pitch in the treble, resulting in a hi-hat sounding more like hiss than the actual percussive instrument that it is. This aspect stands out so clearly that I need no direct comparison to know that the AMG STA-SE sounds significantly less synthetic and more realistic than the original model.
I used two speaker cables: Driade Flow Reference 808 and Jorma Unity. I started with the Jorma Unity speaker cables, which I also use with the Magicos. Then, I swapped to the Driade Flow Reference 808, and I have to say both worked really well with the amplifier. The Jorma provided the most organic presentation with the richest texture and deepest saturation, while the Driade provided an overall leaner, albeit more transparent presentation. I should add that the Jorma Prime demands more than twice the AMG STA-SE’s price and, therefore, is not a realistic candidate. To be fair, the Driades are also not exactly “cheap”. But to get the best from the amplifier, I recommend using the most transparent, neutral, and revealing cables you can afford.
After listening to the little NuPrime for eight days and using the system to compare other review products, I must confess that the amplifier proved more “invisible” than I had initially given it credit for. Although I had observed the differences over the last week, I wondered how much better the A1.5 would still be.
Of course, given the immense disparity in price, the following comments do not affect the AMG STA-SE’s intrinsic performance and are in no way relevant to prospective buyers. But as I have always conducted comparisons with the Big Swiss amp, I can’t stop now, can I?
The AMG STA-SE’s timbre has truly improved beyond the original model and is now indeed much closer to that of the ST-10. But it’s not quite as neutrally natural or well-balanced as the CH. In terms of articulation, control, transient behavior, and dynamics, I have to admit the little NuPrime more or less performs at a similar level. Remarkably for a big power amp, though, the CH also has airier treble, sounds lusher (more free-breathing), is more fluid, and has more delicacy. Compared to the Big Swiss, the newcomer still sounds less convincingly realistic. But to put this into perspective, the AMG STA-SE sounds more natural than all other Class D amplifiers I have heard.
So, the reference-class amplifier still wins, but not by as big a margin as the price difference might suggest. Ultimately, I don’t expect a 2.500 euro amp to perform as well as a 30.000 euro amp, let alone beat it.
Ridiculous comparisons aside, this tells us that the AMG STA-SE has taken an important step forward to sound more like a reference-class Class A/B power amplifier than its predecessor, which is quite an achievement. Ultimately, the main point to take away from this review is that the Special Edition has actually addressed all the areas where I felt it could be bettered. Even if the overall balance has been re-adjusted to achieve this, it sincerely exceeds my expectations of what a 2600-euro amplifier should be capable of.
All products in the NuPrime AMG line have the same stylish housing and the same dimensions. Visually, the AMG STA-SE pairs beautifully with the AMG DAC (as shown in these photos) and just as well with the AMG PRA preamp or the AMG HPA headphone amplifier. Or another AMG STA-SE, of course;-)
Conclusion
With the AMG STA-SE, NuPrime has successfully combined the characteristics of two of their different product lines. It has the full-blooded tonality, body, and robustness of the ST-10 and Evolution STA, as well as the fluidity, refinement, and flow of the original AMG STA. Uniquely, for a Class-D design, it delivers control and musicality in equal measure.
The AMG STA-SE may no longer be the absolute bargain it was in 2020, but I still do not know any other amplifier under 5000 euros that equals it, let alone one that comes close at the same price point.
I realize one cannot hand out rewards for every product, and I’ve already handed out quite a few for NuPrime. But once again, this amplifier ticks so many boxes in such a neat and small package and at such a friendly price point that I have no choice but to hand out another. The AMG STA-SE is wholeheartedly recommended.
External Links
Manufacturer’s website: NuPrime
Distributor for the BeNeLux: Dimex
And, of course the question: did you try two SEs in mono block config? How did that go?
I was supplied with only one SE so I did not do that test at this time. However, I have reviewed the ST-10M monos as well as the AMG STA in mono mode. From these reviews, I know that doubling up a NuPrime amp is very beneficial.
Nice in depth review again sir Punter! Thanks!
The Jeff Rowland models you mention at the beginning of your review were cheaply made amps which used poor connections inside and poor switching power supplies. The only thing about them that smelled of high end was their chassis and brand name. This review just knocked your credibility down about ten rungs on the ladder for me.
I have owned and reviewed several Jeff Rowland preamplifiers and power amplifiers, both their linear and switched ICE and Pascal designs, as well as their DAC, and many of the products are reviewed on this site. There’s also a JRDG company special with all ins and outs of all their products which is worth looking up if you’re interested in the brand.
Pertaining to this NuPrime review, when I recall the original AMG STA, I was not referring to the Class-D Rowlands (which I also do not rate very highly) but specifically to certain classic Class-A/B models such as the model 6 and model 10. Both are linear designs, even if the model 10 had a switching power supply.
Hi Christiaan, Thanks for the answer the other day on Vineshine. Question. As you know I ended up getting a pair of these way back running them mono thanks to your initial AMG STA review. What do you think they would sound like with the SE upgrade?
I’ve not tried the SE in mono but I would assume it behaves the same way as the AMG STA. The SE upgrade improves the tonality and elevates the realism, and for that, it is highly recommended. But to some extent, it also depends on whether or not you want a fuller, slightly darker, and more saturated sound as opposed to the leaner and airier sound of the original. That’s a personal matter. If you feel your balance with the original is ideal right now, I would suggest simply getting a demo first.
Not sure if you recall I have the ML 15As connected to a Bryston 4b3. I had done an A/B test with my new at the time AMG STA. I ended up leaving the Bryston with the MLs because of the warmer presentation. The Mono AMGs (purchased another one) went to my Tektons in another location. Except the Tektons are no more. I didn’t like the sound stage and they were “too large” said…this crazy woman that lives with me. I now have Magnepan LRS+ with the AMGs. So yes the definitively need to be “warmed up”, not warmed up like break in, warmed up like right now jazz sounds flat. Based on what your saying, I don’t need the demo, I should just get the upgrade.
Hi Marc, reading your summary, I would say the SE upgrade would indeed be a good step in the direction you desire. That said, you may still want a warmer or harmonically richer sound with the Maggies. The AMG-STA SE is definitely fuller and richer in harmonics than the origial but it remains essentially quite neutral, which I think is a good thing. But it does not emulate a tube sound, so to say. If that is what you need or want, then the new NuPrime may still not provide what you are after. Ultimately, there’s only one way to find out… I’d be very interested to hear your feedback if and when you have taken the plunge.
HI Christian, in the past you have made comparisons between the various Nuprime power amps with close attention to the Evolution STA as the gold standard. I don’t see the Evolution being mentioned in this review at all for comparison, why is that??
Hi Luke, well, the AMG STA SE is the successor of the AMG STA, so it makes sense to compare the two. The Evolution STA sits in a different price range. But it also sounds quite different, making it hard for me to provide any meaningful comparisons to the AMG STA variants based only on memories.
OK thanks I am evaluating the amg sta se now and after nearly 400 hours of burn in it is now beginning to show itself to me as a much more accurate and somewhat different sounding (in a good way) unit compared to the standard version.
Hello,
How does it compare with NAD M23 ?
Thank you
I have not heard the M23.
Hi Christian,
I just received the upgraded SE version of my 2 amps in mono setting and I have to say, this is a nice jump to higher quality. To make it short it sounds more real, more transparent with more additional details, more dynamics, deeper stereo imaging, tighter bass. Everything is more precise. Easy to have goosebumps listening a voice here or stamp your foot listening a band.
It’s a no brainer upgrade for everyone looking the cost vs the benefit and we can congratulate Nuprime to propose this option. The French distributor never answered to my calls nor my emails, and I contacted Nuprime in Taiwan to do so. I received all instructions to proceed through their tech support in Hungary (Krisztian thanks!).
You said it sounds like Pass Lab amp, I had one integrated in the past, I much prefer this Nuprime combo by far.
Thanks for the very nice feeback, Phil!
Does Phil have any disclaimers he’d like to add, any association to NuPrime perhaps, cause Phil’s review sounds an awful lot like a marketing piece.
I do not have any link with the hi-fi world, I’m just an happy customer after 40 years of up and down with products and sometimes expensive products. It’s not so often a manufacturer proposes an upgrade which is accessible. And not often a brand cares about the request of a customer and delivers.
Martin Logan is also one of them from my personal experience as well.
Well then, heck of a review of their upgrade. Sounds like a no-brainer upgrade. One thing I did already agree with, it was nice they offered the upgrade to existing customers at the fair price they did. The AMG amps weren’t that old, simply replacing them with a newer model that fast would have been frustrating.
I also purchased these with new boards and can say it was certainly a step up from the original version and although I had the original boards I had no intention of reversing them. However, I have found the Audio GD master 2H monoblocs drive my system much better.
More than a month after the SE upgrade, Î’m impressed by the music delivered here,
Just so realistic, so fun ! confirming my initial post.
Thèse little amps are a true value I will keep Théo for a long time. Amazing.