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  7. Struss Audio DM 250 English ver.

Struss Audio DM 250 English ver.

Link do zapowiedzi (en): Struss Audio DM 250

Opinion 1

From today’s perspective this might sound a bit comical, but a long, long time ago, and by this I mean a quarter of a century ago – the second half of the nineties, the Polish audio market was quite different to what we see today. Most sellers existed in basements, garages or was adjacent to the main business of their owners, usually in very industrial areas, only the biggest players of today (like Audio Klan, which started working in the mentioned times) could afford their own “shop”. Also in those days the brand press was not only issued on glossy paper, but there were also some titles, which were similar to some underground press or a fan-zine, like the “Magazyn Hi-Fi”, which had their devoted followers. Many of the Polish audio companies begun then, just to mention manufacturers like Ancient Audio, Artline, Audiowave, Chris Sound Research, ESA, GLD, Nuda Veritas, QBA, RLS, Sound Project or the hero of our today’s test – Struss Audio.
I remember clearly, that, when we forego the High-End constructions from abroad, which remained in our dreams, the products signed by Mr. Zbigniew like the integrated 140 and the top model S seemed to be the fulfilment of audiophile dreams. But time flows constantly and the market verifies the abilities to adjust to the changing environment, and when someone lost attention for a moment, then he or she was out of the game. Fortunately Struss Audio reminded us of its existence, once in a while, in 2001 with the model Q, in 2002 – the Chopin (presented during the Audio Video Show together with loudspeakers of a Polish brand, which does not exist anymore – A&H), in 2009 – the might R500 (on the AVS it played with the very intriguing loudspeakers Morel Fat Lady), the updated Chopin mk. IV from around the same time, or the “completely new concept” R150 (2012). There was always something going on, and we were somewhere around that manufacturer, sometimes closer, sometimes further away, until the last edition of the AVS, where on the ground floor of the Sobieski Hotel, in the room Gallery I, we encountered the prototype power amps MPA 400, Class-A, which inspired our today’s encounter with the integrated DM 250. We started talking, and it turned out, that we have some common ground, the manufacturer wants to hear our opinion about its current offerings, while we are interested in have a look and a hear. But as it usually is in such cases, before we could come to final terms, it turned out, that the vacation time is over. But the integrated reached us, so we cannot do anything else, than to invite you to read our very subjective tale about how we perceived it in our systems.

But let us start from the beginning, from the looks and first impression, which we caught during our usual photo session documenting the unboxing. It cannot be denied, that the Struss DM 250, despite the absolutely traditional form in terms of size and design, looks splendid. Our eye is caught by the intriguing, split, black fascia, with the coral-red insert giving it a sense of lightness. This insert is also the basis for the blue LEDs informing about the active source, and the chrome plated knobs used to select the sound source (the smaller one) and the volume (the larger one). Just beside those there is the IR sensor and on the other end of the front panel there is the company logo and a lever power switch from the American company C&K, equipped with a protection against accidental power on or off of the device. The left part of the top cover is covered with holes allowing for appropriate ventilation. You can also look inside the cover through those holes to see, where the hefty 16kg of weight is coming from.
The back plate is not disappointing either, as we have four line inputs at our disposal – three RCA and one XLR, a phono input – dedicated to MM cartridges, a preamplifier output and a direct to power amp input. The single loudspeaker terminals come from WBT, and their looks reminded me of the Electrocompaniet ECI5 MkI (as the MkII used the much less user friendly plastic coated ones). The amp is accompanied with a very simple – it allows only for volume control – remote, which is also surprisingly heavy (0.37kg).

From the construction point of view, the DM 250 is a representative of new generation of amplifiers, which is based on three decades of experience, but uses many contemporary technologies. It is worth mentioning, that bipolar transistors were excluded from the amplification path, so the 250 is a pure FET amplifier. Secondly, in the preamplifier section there are no capacitors, it uses a J-FET based HPCS (Harmonics and Phase Conversion System) circuit, which generates even harmonics and reverses the signal phase. In short, this is a kind of “simulation” of a vacuum tube circuitry, without the shortcomings of the latter, while adapting the construction to the “physiological characteristics of the human hearing”. Another interesting twist was made in the phono preamplifier, where the RIAA curve was modified by adding a time constant 3.2 µs (Neumann).
Except for the mentioned “attractions” the 250 is a classic. In the power supply we find two solid, toroidal transformers, 500 VA each, and four 15 000 µF capacitors from Nippon Chemi-Con in a dual mono setting of the complete amplifier. It is not a symmetrical device, so there is a proprietary desimmetrizer attached to the XLR inputs.

Moving on to the listening part, I had a thought in the back of my head, about how much of those old, archival Struss amplifiers remained in the 250. Did Mr. Zdzisław allow himself to keep the “arch offensiveness” of the 140, or rather went for the refinement and nobleness of the last version of the Chopin, or maybe the might of the R500? As it turned out, a new beginning is a new beginning, and while looking back might have a sentimental aspect, it is much better to look at the horizon … and below your legs, to not to fall. This is why it is worth giving the 250 a carte blanche and just let her play. And in this case, the sooner we do it, the better, as the new Struss integrated just cannot stay silent. The DM 250 offers a sound, with a surprisingly big volume, nice freshness and dynamics capable to push you into your seat. And in addition it keeps a master resolution in almost the full frequency spectrum. So when you look at this abbreviated characteristics, shortened for the introductory chapter, you should not be surprised by my choice of test recordings. I reached for great symphonics, so the album created with the cooperation of the London Philharmonic Orchestra and the Finnish formation … Nightwish – the album “Dark Passion Play”, and then, as a kind of antidote to the sweet vocals of Anette Olzon, the “old” good Tarja on “Once”, where the mentioned Londoners did also appear. Yes, the classic symphonic metal, where the primate growl intertwines with women’s voices and the string section fights with the guitar riffs for the listener’s attention. But this apparent turmoil has one big advantage – with the present congestions and multiple layers of sound, the amplifier either can handle it, or throws the towel on the ring after first track and asks for a lower sentence, like “Hotel California” the Eagles. The Struss did not ask for any special treatment and gave my Dynaudio Contour 30 and our neighbors a nice treat, as they received a two-hour spectacle of Scandinavian decibels for free. It was loud, quick and aggressive when needed, but I was not able to force the 250 to show any signs of compression, flattening of the sound or offensiveness. There was full control over the reproduced sound spectrum, although when the recording contained the lower frequencies drawn with a thicker line, the Polish integrated did not try to correct, or contour that in any way.
In terms of spaciousness, the “Amused to Death” Roger Waters as well as the more neutral, in terms of propagation of reverb, “Antiphone Blues” Arne Domnerus or “Monteverdi – A trace of Grace” Michel Godard sounded very suggestive and “wide”. This does not mean, that the Struss does not build the stage in depth, because it does, and on a very satisfactory level, but the width is more accented here.
The temperature of the sound is treated similarly – it can be described as neutral. You cannot find any signs of warming or cooling, what, on one hand, allows us to freely model the sound of our system by appropriate choice of other elements of the sound path, including cabling, to which the 250 is sensitive, on the other hand, it requires some common sense when choosing your system. This because the Struss does not try to mask anything, and while it can discipline loudspeakers with too slow bass, by keeping it tight, it will not tame or round off a too ecstatic treble.
And what about the only “add-on”, the phono input characteristic? You should not think, that having a not so refined cartridge and a light deck, prone to vibration, we could approach nirvana. But with a well sounding, saturated and heavy turntable, the Struss will give the whole lots of very nice breath and freedom, and by doing that, it will extract some audiophile treats, we did not realize were there.

Based on the listening sessions of the tested amplifier Struss Audio DM 250, I can claim, that the family DNA of this device, which stems from the previous century, was preserved to a large extent, while being also very thoroughly ennobled. We deal here with a very direct sound, quick and dynamic, while being noble and refined. Maybe, at first sight, the 250 does not enchant and subdue us with tube passion, but its transparency and neutrality are better suited for the future, than a mannerism of sound, which could become its curse, once the initial excitement is over.

Marcin Olszewski

System used in this test:
– CD/DAC: Ayon CD-35 (Preamp + Signature)
– Network player: Lumin U1 Mini
– Digital source selector: Audio Authority 1177
– Turntable: Kuzma Stabi S + Kuzma Stogi + Dynavector DV-10X5
– Phonostage: Tellurium Q Iridium MM/MC Phono Pre Amp
– Power amplifier: Bryston 4B³
– Loudspeakers: Dynaudio Contour 30
– IC RCA: Tellurium Q Silver Diamond
– IC XLR: Organic Audio; Vermöuth Audio Reference
– Digital IC: Fadel art DigiLitz; Harmonic Technology Cyberlink Copper; Apogee Wyde Eye; Monster Cable Interlink LightSpeed 200
– USB cables: Wireworld Starlight; Goldenote Firenze Silver; Audiomica Laboratory Pebble Consequence USB; Fidata HFU2
– Speaker cables: Signal Projects Hydra
– Power cablese: Furutech FP-3TS762 / FI-28R / FI-E38R; Organic Audio Power + Furutech CF-080 Damping Ring; Acoustic Zen Gargantua II; Furutech Nanoflux Power NCF
– Power distribution board: Furutech e-TP60ER + Furutech FP-3TS762 / Fi-50 NCF(R) /FI-50M NCF(R)
– Wall power socket: Furutech FT-SWS(R)
– Anti-vibration platform: Franc Audio Accessories Wood Block Slim Platform
– Ethernet cables: Neyton CAT7+; Audiomica Laboratory Anort Consequence
– Table: Rogoz Audio 4SM3

Opinion 2

The Polish brand Struss Audio is recognized with a lot of certainty by more than half of the music lovers. Why? As it often happens, during the last dozen or so years, the company endured not only good times, which allowed it to find its way into our minds, but also some worse ones. The better were marked with models like the 140 or R500, which found their fans, while the worse were the result of the brand disappearing from the market, for unknown reasons. Fortunately, not only for the manufacturer, but also for the potential buyers of the new incarnation of Sturss, the constructor did not lose his interest to introduce new models into his portfolio, what resulted in our today’s attempt to present you the newest effects of the work of engineers of the company, the integrated amplifier Struss DM 250, which was supplied for the test by manufacturer himself.

Describing the looks of the tested amplifier, theoretically I do not have any reason to use adjectives like “design marvel” or similar. But countering any potential malcontents, I inform you, that maybe the pictures do not reproduce this fully, but in real life, the amplifier, besides being a solid piece of engineering – it is very heavy despite the modest size, has very interesting exterior. I really like the front, with the milled wave, broadening to the right, where in the immersion, the red colored metal gives a tad of aggressiveness to the looks of the amplifier. On the left we have a lever switch for the power, together with the silvery company logo, placed just above the red insert, while on the right, on the indented part, we have six LEDs indicating the active input, with the input selector just next to those, and most to the right the volume control knob. Due to the fact, that the two large transformers are placed to the left of the chassis, above them four panels of rectangular holes were cut, to allow for appropriate ventilation. The panel on the back, is also quite crowded. From the left we have a ground bolt and a set of inputs/outputs: the optional Phono, CD-DAC, XLR, further four RCA connectors, then single loudspeaker terminals and an ICE power socket with integrated fuse. A nice add-on to the 250 is the nicely looking remote control for the sound volume.

You might be surprised, but approaching the listening session of this amplifier, I was not very acquainted with the previous models of this brand. Yes, I met one or two somewhere, at somebody’s place, but this was never a representative listening session, which would give any ground for drawing conclusions or formulating any opinions. Is this bad? Not at all, as having a clean start usually allows for assessing the sonic abilities of a given machine without looking at the past. So how did I perceive the tested amp? Very good. Of course it could not compete with the competition of my system, but it could easily create a phenomenal, well dimensioned, virtual sound stage in my room, on par with that, what renowned manufacturers can offer. The main aspect of the presentation was the resolution, the amp presented lots of information, and that based on a splendid bass. Of course this does not mean that the midrange was not treated appropriately. However, taking into account the character of my loudspeakers, this part of the sound spectrum was treated as a kind of supplement to the extremes, and not the superior goal of the sound created by the Polish product. So trying to define the way of sounding, proposed by the new incarnation of Struss Audio, I can clearly state, that we deal here with a rather neutral aesthetics, yet far away from placing speed and analysis above everything else. If any of you has now a warning light flashing, then I would like to inform all the panicked, that they do not need to worry, because even I, being a relentless enthusiast of saturated sound, got enchanted by the Struss, and this should mean something. So what did convince me to it? Interestingly reproduced music. What kind of music? This is a silly question. Classical, rock and vocal music. Any details? Of course. I started with classical in the form of the 8th symphony of Dimitri Shostakovich. The swing and energy of the mad intervals combined with quiet passages made me sit on the verge of my chair and wait for what will happen in a moment. And if you know the works of this composer, then you also know, that there are things to be afraid of, in the good sense of that word. In short, the immediateness of the attack, its mass and energy were shown without the slightest issues. The next item was the, not so well recorded, Slayer “God Hates Us All”  . So why did I use a disc, which is not of highest quality? Well, this disc, a killer for many audio systems, allowed me to discern between true resolution and a trick, used by many audio designers, being a slight brightening of the sound, which is perceived as the music being reproduced with greater freedom. And you know what, I did not make any mistake. Of course on the top part of the High End segment you can extract more information from the music, but that what the 250 offered, the nice insight into the badly recorded vocals and instrumental virtuosity of the musicians, was a very interesting, I might even say, for many people the preferred way of handling this kind of material. Finalizing today’s test, on the reader landed the last Anna Maria Jopek album “Ulotne”. What was the result? Maybe due to the fact, that the midrange is not overly saturated, it cannot be described as seductive, but even without any good will, I could not be claiming, that it missed anything. It was just even in the whole sound spectrum and without any artificial thinning of the voice of the mentioned artist. And this shows, that the newest product from Struss Audio can even hold itself against productions, needing some extra boost in the midrange.

The analysis of the above shows clearly that in case of approaching the tested amplifier in our own system, we need to take into account its sound temperature. For obvious reason, when we search for something, that will put on weight to our not so well combined set, then the result of this marriage can be far from our expectations. But if we search for something offering freshness of sound, but with its weight conserved, then the tested amplifier can be the cure for every illness. But will this happen? Well, like I said, this will depend on the system it will work with. But to add a tad of optimism, I will mention, that despite the slightly different priorities in my musical karma, this amplifier, putting the tonal balance on the first place, showed me something interesting. What? It showed, that listening to music in a slightly different aesthetics than I do every day, does not always end in less emotions being transmitted through it. And such ability is a very good prognostic for the future, when you are searching for the holy grail of audio.

Jacek Pazio

System used in this test:
– CD transport” CEC TL 0 3.0
– DAC: dCS Vivaldi DAC 2.0
– Reference clock: Mutec REF 10
– Reclocker: Mutec MC-3+USB
– Shunyata Research Sigma CLOCK
– Shunyata Sigma NR
– Preamplifier: Robert Koda Takumi K-15, Boulder 1110
– Power amplifier: Reimyo KAP – 777, Boulder 1160
– Loudspeakers: Trenner & Friedl “ISIS”
– Speaker Cables: Tellurium Q Silver Diamond
– IC RCA: Hijri „Milon”, Vermoutch Audio Reference
– IC XLR: Tellurium Q Silver Diamond
– Digital IC: Harmonix HS 102
– Power cables: Harmonix X-DC 350M2R Improved Version, Furutech NanoFlux NCF Furutech DPS-4 + FI-E50 NCF(R)/ FI-50(R), Hijiri Nagomi
– Accessories: Harmonix TU 505EX MK II, Stillpoints ULTRA SS, Stillpoints ULTRA MINI, antivibration platform by SOLID TECH, Harmonix AC Enacom Improved for 100-240V, Harmonix Room Tuning Mini Disk RFA-80i
– Power distribution board: POWER BASE HIGH END
– Acoustic treatments by Artnovion
Analog stage:
Drive: SME 30/2
Arm: SME V
Phonostage: RCM THERIAA
Step-up: Thrax Trajan

Manufacturer: Struss Audio
Price: 4370 €

Technical specifications
Power: 130 W/8 Ω (2 x 10 W/8 Ω class A), 250 W/4 Ω
Frequency response: 5 Hz – 250 kHz – 3 dB / 1 W / 8 Ω, 10 – 30,000 Hz: ± 0.1 dB
Output impedance: 0,10 Ω
Distortion THD: 0,1 % przy mocy 1 W/8 Ω; 0,025 % @ 130 W/8 Ω
Slew rate: 150 V/μs
Signal/Noise ratio: 135 dB (IHF – A)
Inputs sensitivity:
RCA: 500 mV (RCA), 250 mV (XLR), 3 mV (MM Phono), 0,775 V (power amplifiers)
Inputs Impedance: 100 kΩ RCA), XLR: 22 kΩ (XLR), 47 kΩ (MM Phono), 47 kΩ (power amplifiers)
Power consumption: 40 VA – 800 VA (peak)
Potentiometer (volume): the highest precision model from the Alps – Blue Velvet
Transformers: 2 x toroidal, magnetically isolated 500 VA each
Capacitors filtering the supply voltage: 4 x 15 000 μF – Nippon Chemi-Con
Dimensions (W x H x D): 430 x 102 x 338 mm
Weight: 16 kg

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