Jim Rivers


James Darby




The Lyngdorf SDA-2175 is a "semi digital" (more on that later) power amplifier rated at 200 watts per channel @ 8 Ohms and 375 @ 4 ohms. The retail price is $1,800.

It has fully balanced gold plated XLR inputs and regular RCA gold plated inputs as well. As you can see, there is nothing unique in the Lyngdorf's appearance, though it does come in either silver or black. The front panel sports and on/off button and two pale green lights - on that indicates power on and the other shows "operate" when the amp has finished its delayed startup/safety check routine. We normally save additional claimed specifications for the end of the review, but they are so significant that we will publisher them here:


Frequency response 0.3 Hz – 33 kHz -3 dB points, 8 Ohms load.

Frequency response -0dB/+0.2dB 20 Hz - 20 kHz, 8 Ohms load

Frequency response -0.2dB/+0dB 20 Hz – 20 kHz, 4 Ohms load

THD+N, 1 W /8 Ohms 0.004% A-wgt.

THD+N, 1 W/4 Ohms 0.006% A-wgt.

THD+N, 100 W/8 Ohms 0.01% A-wgt.

THD+N, 180 W/8 Ohms 0.07% A-wgt.

THD+N, 275 W/4 Ohms 0.07% A-wgt.

S/N ratio 117 dB A-wgt. ref 200 W/8 Ohms.

Channel separation 84 dB 1 kHz, 200 W/8 Ohms.


Pretty impressive and also very specific - something not always found in amplifier specs. It seems this is a case of "if you got it, flaunt it". Good for them.





Lyngdorf audio was started in 2005 by Peter Lyngdorf. Let's let him tell us about the chronology of the company;



“In 1996 I started a technology project which in 1998 led to the launch of the world’s first fully digital amplifier. This was seen as a revolution within hi-fi, and led to the establishing of TacT Audio ApS. Since then TacT Audio has been recognized as the leading company within digital amplification and room correction.


 Now the time has come to move on.


Lyngdorf Audio is the natural successor to TacT Audio ApS, and generates the same high level of innovation. We will continue developing even more ground-breaking products within the digital domain, thanks to an increased level of investment in the company."


Indeed. The TacT/Lyngdorf relationship is still in evidence as the box in which the 2175 arrived had the TacT logo rather than Lyngdorf.

No biggie.






Lyngdorf Personnel




"The SDA 2175 is a high-performance semi digital amplifier designed without compromise. It acts as a controllable slave amplifier in Lyngdorf Audio active speaker systems or as a power amplifier for external pre-amplifiers."


"Peter, why is the amp called "semi digital"?


"The output stage uses Pulse Width Modulation with a patented switch speed optimization technology. This ensures a low natural distortion, and an unmatchable performance is achieved by using less feedback than other Class D amplifiers. Careful and sensitive design touches can be seen throughout the amplifier: it starts at the mains input with a low-noise Holmgren Toroidal transformer with power supply feed-forward compensation, suppressing the variations in the output rather than relying on feedback-based error correction as in conventional amplifiers. This technique originates from the design of the Millennium, but can also be used in semi digital amplifiers.

The SDA 2175 employs a fully-balanced topology. If the switchable input is driven from a balanced source the signal is kept balanced all the way through the amplifier to the PWM conversion stage. This guarantees a remarkable performance with a signal-to-noise ratio superior to any other Class D amplifier in the market. In the critical output stage only the highest quality components have been used, e.g. polypropylene capacitors and linear ferrite material in the output filter. Combined with other techniques this means the SDA 2175 benefits from low and frequency-independent distortion. Consequently wideband musical instruments can be reproduced without any added harmonics – any source will be recreated to sound the way it was recorded.


The entire amplifier is well-packed in a solid aluminum chassis featuring extremely good build quality. Aluminum is non-magnetic, but is still capable of shielding against high frequency RF interference. Even the bolt holding the mains transformer is made from non-magnetic stainless steel. Not only does this construction please the eye – it also acts as a rigid and vibration-free environment for the electronics."






It is really nice when the owner of the company does some of our work for us, but now it's our turn.

First, here are some comments, pro and con, on the 2175 from our Shootout:


"More delay between the two guitars, nice; airy highs; good detail; good dynamics and therefore the music is reproduced with good speed and pace; if you like sharp and crisp sound this amp has it; upfront and forward (this could be bad to some people)"


"Preferred Lyngdorf because: Musicality is better with this amp, even though not quite as detailed."


"Nice fullness, highs not etched; good drive and dynamics; good detail level; warmer with strong bass; very relaxed sound; detailed and open with a touch of warmth."


"Preferred Lyngdorf because: A little greater sense of air and space, more musical of the two."




Jim Rivers on the SDA 2175


 I was recently given the opportunity to audition three "emerging technologies" amplifiers. Flying Mole's MA-S160, Cary's CAA 1 and Lyngdorf's SDA 2175. Since most of my in home listening is through modified and rebuilt tube amps, I was somewhat apprehensive of the transition to these Class D amps.


 Listening sessions were through JM Labs Daline 3.1 speakers in my small, two channel room. Later in the week, listening was on the much larger system, through GR-Research Alpha LS speakers.


Stacey Kent: The Boy Next Door,  Track 1 and 2

B'ela Fleck: Flight of the Cosmic Hippo Track 4 

Nanci Griffith: Once in a Very Blue Moon, Track 10


Katie Melua: Piece By Piece, Tracks 1, 2 and 4

Jennifer Warnes: The Hunter, Tracks 1, 7 and 8

 Lorin Grean: Hand Woven, Tracks 1, 2 and 9

The music was chosen from some of my favorite CD's and includes male and female voice in addition to acoustic instruments like guitar and harp. I also included CD's for bass or for sibilant tests.


After at least an hour of warm up, the Lyngdorf began doing some nice things. It had tight, controlled bass in my small room. In the larger system, the bass exibited outstanding control. A very pleasant presentation. This was apparent in both systems. In the larger system there was a much more forward and layered soundstage compared to the other two amps.




 James Darby on the SDA 2175




For several reasons, I spent much more time comparing and evaluating this amp that was intended. First, I had already spent a great deal of time with other "digital" amps and comparing it to all of them was quite an undertaking. Here is the list:


Halcro MC20 (my reference)

Cary CAA 1

Dolan M1 monoblocks

Sonic Super T Amp

TrendsTA 10.1

Kingsrex TA20


As well as these non-digital amps that were in house under review at various times:


Art Audio Carissa

Jolida 300B

                                                         Armonia by Nightingale

                                                         AES Super Amp MkIII

                                                        Audio Space Galaxy 88

                                                   And my reference integrated LSA Signature


That's TWELVE amplifiers. Some high powered, some low. Some tube, some class T, some Class D and even a hybrid. Some very low priced and some much higher.


Why? I was intrigued by the sound of the Lyngdorf. It is different than the other "emerging technologies" amps and actually more similar to the others, so I wanted to explore why that is.

After listening to dozens of recordings of all musical genres and various formats, there is one quality exhibited by the Lyngdorf that stands out. One that it shares with some very special amplifiers and makes it excel over others, regardless of price. Almost everyone who listened to the 2175, either in the shootout or over a longer term, picked up on this quality. They called it "musicality". I call it Mojo. The Lyngdorf has gobs of Mojo.


Have you ever looked at a bunch of vacation snapshots and have one or two just leap out at you because somehow they captured the essence of the moment in a special way? The emotion, the memory, the overall core, crux, spirit, soul or meaning of the person, place or thing? It is true that a picture says a thousand words - it's just that some say them so much better than others. The Lyngdorf is one of those.


It is not a matter of ultimate detail, soundstage, airyness or other approved audiophile terms. It is not even the ability to convey a "you are there" quality. I have heard live performances that were not very "musical." In 1964, Justice Potter Stewart tried to explain "hard-core" pornography, or what is obscene, by saying, "I shall not today attempt further to define the kinds of material I understand to be embraced . . . but I know it when I see it." So, in a rather quirky way, musicality or Mojo is like porn...except you know it when you hear it.



There are amplifiers of all classifications that have greater detail, bigger, deeper, wider and fuller soundstages, more accurate timbers, etc, but not too many have more mojo. Some may even quantify this quality as being forward or aggressive because they cannot find the words to describe what we've been talking about here. The 2175 is neither. It does render a very deep soundstage with exquisitely defined layers and some of those layers bulge out a bit in front and to the sides, but only to make room for the others behind them. That is not "forward". Some might say that the soundstage is a tad exaggerated and that may well be. There is a sense of power present, but not limitless power. If you have very low impendence speakers, say below 4 ohms that are not especially efficient, you could clip it. That was the case with the Mark & Daniel Maximus Monitor. With the much more benign Sason LTV, the Lyngdorf was able to drive them to ear-splitting levels without undo strain. It will let you know when it is reaching its limits by becoming somewhat congested, but you really have to press it.


With the ultra efficient Cain & Cain's, the Lyngdorf of course was merely idling, but it did show a bountiful amount of low level detail and microdynamics.  Like all the other solid state amps, the Cain's turned a very cold shoulder to it. Their motto seems to be "Give me Single Ended Triodes or give me death!" But of all the non-SETs, the Lyndorf fared the best.


The amp's ability to reproduce large dynamic contrasts was apparent in Ron Nelson’s Rocky Point Holiday, another incredible HDCD classical cut from this Reference Recording's– Wonderful detail and huge soundstage"Tutti" CD. The first few measure start softly an build and build to a crashing crescendo that many amps simply cannot cope with. The Lyngdorf delivered.


It also shown on Karen Carpenter's deliciously rich alto on "Solitaire" - not too warm or mushy with good definition (you can hear the saliva in her mouth), but never etched or scratchy.

Like mercury, the 2175 is fast and liquid, but not metallic at all.



My own piano solo recordings had a naturalness that I'd call near the top tier at any dollar amount. My 24 bit digital electronica sounded studio quality through the Sasons. There is not even a hint of digital glassiness. It sounded very linear throughout the bandwidth no sign of trouble at the critical digital crossover point. I was unable to pinpoint a specific character or coloration to the sound. While is has power o' plenty, the bass is not overtly muscular to the point it calls attention to itself. It just is what it is.The mids are smooth and love vocals, while the highs have that silky quality that made high-end Japanese tube amps famous. This amp might

Can the Lyngdorf rock? Absolutely! Led Zep, Stevie Ray, The Who and AC/DC were all well served with slamming snares and kickin' kickdrums. Electric as well as acoustic guitars were rendered with all attendant guts and gore or unamplified zing when necessary. Again, with reasonable large or small speakers in most sized rooms, the Lyngdorf will fill them with what you want to hear.

be easily mistaken for a very high quality tube amp, especially if it has a valver in front of it as a preamp.Do not mistake that for suggesting it is "warm". It's not. And neither are good tube amps. Describing tube amps as "warm" is as silly as calling Bose "high-end". Both are fallacies propagated among the  inexperienced or unenlightened masses.

The Lyngdorf never trips or stumbles, but it does fall a bit behind in the ultimate, top tier tube Mojo meters. Joe Fratus' Carissa 845 tube-based power amp is meatier and even more musically magical than the Lyngdorf (but at much less watts per channel), the monoblock Dolans (an ICE chip-based system) also trump it in channel separation and 3D detail and clarity.

The Halcro may be a bit cleaner but also a bit drier with a greater sense of power through its 400 wpc.

The Armonia by Nightingale is warmer and more sensual and the LSA Signature integrated is a better all round package.

If I had to rate this group of amplifiers in musicality or mojo alone, regardless of price of power rating, it would look like this:


Art Audio Carissa

Dolan M1 monoblocks

LSA Signature Integrated

Lyngdorf 2175

Armonia by Nightingale

Cary CAA 1

Jolida 300B

Adio Space Galaxy 88

AES Super Amp MkIII

Kingsrex TA20

TrendsTA 10.1

Sonic Super T Amp



If I had to assign a "bang for your buck" VERY subjective valuation, taking features, power ratings, construction, versatility as well as sound quality into consideration, the list might look something like this:

LSA Signature Integrated

Lyngdorf 2175

Halcro MC20

Art Audio Carissa

Amonia Integrated by Nightingale

Audio Space Galaxy 88 Integrated

Cry CAA 1

Jolida 300B integrated

Kingsrex TA20

Sonic Super T Amp

TrendsTA 10.1

AES Super Amp MkIII






At $1,800 and featuring balanced operation, the build quality and sound quality makes the Lyngdorf an outstanding value in a true high-end quality, powerful amplifier.

Be advised that the stereo amp is not bridgeable to use as a single mono amp. Other than that, we cannot think of any reason not to make the Lyngdorf 2175 a part of your system.