Product Review

Simaudio/MOON i-5 Integrated Amplifier

October, 2002

Arvind Kohli





Power: 70wpc @ 8 Ohms, 110 wpc @ 4 Ohms.
MFR : 10 Hz - 70 kHz, -3 dB
Input impedance: 14000 Ohms
Damping factor: >200
Slew rate: 20V/microsecond
Sensitivity: 300mv to 3.0 V rms
S/N: 97 dB @ full power.
THD: 0.1% (20 Hz  -  20 kHz @ 1 watt)
Remote: Yes
Size: 4"H x 17"W x 15"D
Weight: 26 Pounds
Available Finishes: Black or Silver Faceplates
MSRP $2595

Simaudio Ltd.


At a certain point in the journey to audio bliss, you start to realize that simplicity may be the most direct path to your goal. But, we would not be audiophiles if we were satisfied with a simple design alone. The entire pursuit in the audiophile's life can be summed up by the term refinement.

All things being equal, integrated amplifiers (preamplifier and power amplifiers in the same chassis) are a simpler approach to the power amp / preamp combination that has long been the heart of the hobbyist's system. But for quite a few years now, many high end manufacturers have been paying increasing attention to integrated products. Today we can find a great selection of these units by a variety of companies that have wrapped their entire existence around the pursuit of refinement. By reputation alone, Simaudio stands out at the forefront of these companies. The following is a review of their i-5 model, and my findings on the product.

Company Profile

Simaudio was founded by Victor Sima in 1980 under the name SIMA, the company started out designing and producing professional audio equipment. Two years later they ventured into consumer electronics, and in 1988 the name was changed to Simaudio.

The Celeste line introduced in 1992 incorporated what they called “Renaissance" technology. John Poulin, the then Director of Operations purchased Simaudio in 1994 and launched the MOON amplifiers and preamplifiers with further refinements, known as 'Advanced Renaissance' technology.

The Simaudio philosophy aims for the long term use of products and are against forced or premature obsolescence. They pledge to never manufacture a product under a certain level of performance, where the lower limit is determined by 1) the costs associated with high quality electronic component, and 2) the R&D investment to achieve a long lasting and durable design.


An unfortunate turn of fate awaited the first review sample. Shortly after turning it on, I started to hear loud pops when I toggled through the inputs, and shortly after the amp went dead. The very friendly and understandably embarrassed folks at Simaudio apologized profusely, and expedited a replacement unit. Lionel Goodfield, the VP of Marketing, later explained the cause to be a loose ground that possibly could have been caused during shipping. The overkill 10 years warranty (for original owner only) would certainly cover any such mishap.

Burn-in is suggested at 6 weeks, and the unit is designed to be left on at all times, hence the power switch on the rear panel. I plugged the i-5 and my source components into my PS Audio P300 power regenerator, as I consider this to be a big benefit to an amp that has modest power needs. There is no way my Bryston 4B Pro can even be plugged into the P300, even without a signal. It took me about three months of diligent burn-in before I started serious listening.

Unfortunately, I cannot honestly report on the change in sound when it takes that long, I would not trust the human memory to remember differences that small over that period of time. You can remember impressions, but I do not like to base my reviews on impressions since they are so subjective. All I can say is that I did like the sound right out of the box, and I really liked it the day I sent it back (with a tear in my eye).

My primary listening room has the speakers against a 14' wall and an 8” opening on the opposite wall. For casual listening, the speakers were placed 7' apart, and 9' from the tweeters to the listening position. For critical listening sessions, all three points were about 7' from each other, and well away from room boundaries.

My listening tests were done at two listening levels that were set using a -20 dB, pink noise signal. The two levels were set at 60 dB and 80 dB from my listening position with the help of a Radio Shack SPL meter. The 60 dB level approximates my ‘normal' listening level when there is little or no ambient noises, and this is usually late at night or I am home alone. The 80 dB level is about as loud as I ever listen to music, and this level is only used when I am home alone for the sake of marital bliss.

The Outside

The review sample was supplied in a black faceplate, silver is also available as an option. The front panel has a LED display, a large volume knob, buttons for power, mute, input toggle, tape monitor and display toggle. I really like the simplicity of the layout, although I would have passed on the large, bright LEDs and the badge if it were possible. Sorry, there is no headphone jack, but it would have been nice for late night listening. The remote is as simple and easy to use as the faceplate, and it also adds the balance function.

The rear panel has a set of five-way WBT speaker connectors per channel. Inputs are via five RCA sets labeled CD and A1 thru A4, and two outputs in the form of a pre-out (variable) and a Tape Out (fixed level). Personally, I feel the pre-outs are very important, because they allow for integrating a subwoofer or bi-amping.

Be VERY, VERY CAREFUL with the A4 input. Its signal is not routed through the volume control, so it plays the signal at full strength. You may be lucky and not damage any gear, but it certainly will scare straight the wrinkles in your shorts. This input is intended for sources with their own volume control, like a surround processor or the pre-out on an HT receiver. This is actually an excellent concept, for it allow integration of an outstanding two-channel system into a less ambitious HT setup, with the main speakers and their amplification being common. I would be happy if the A4 input were capped and had a warning label on the rear panel, because the mention in the owner's manual is not precaution enough. To be honest, if I were not reviewing products I would probably never read the manuals. You can also reset the input to be routed through the volume control, but I would not trust my memory to remember which setting it was last at. My solution was to make sure I never used that input at all.

I really liked the design of the heatsinks on the side. The rounded sides with lateral fins are not only visually appealing, but also provide better ventilation of each fin . . . very smart.

The Design

Simaudio has determined four critical areas of preamplifier design:

1) A "lean design" achieved through the shortest possible signal path with the intent of eliminating all potential sources of signal interference. In the case of the i-5, the path is only 15” in length from input to output connector. The typical path length in an integrated will probably be 20” to 25”.

2) Minimizing signal path obstacles through the use of an open-loop zero overall feedback design that eliminates both capacitors and carbon-based parts. There is one step of local feedback at the output stage to maintain low THD.

3) The i-5 uses a Crystal Semiconductor unit for its gain stage that is said to produce no colorations at any setting, similar to the in-house designed "RBG" shunt-to-ground circuit topology , found in the P-5 preamp. This was done to save space and reduce the signal path.

4) A power supply featuring proprietary toroidal transformer to improve precision and control of the musical signal. More on the transformer below.

The preamp operates in class A. The amplifier section is fed by a 500VA transformer built in-house by a very arduous process, as described in their white paper. It is said to have a regulation factor of 6%, compared to typical transformers with a regulation factor of 15% to 20%. This is very significant as I will explain later. The total capacitance is rated at 40,000 microfarads, and the output devices are two Motorola bipolar units per channel. The amp is capable of a continuous output of 9 amps and a peak of 16 amps.

'Renaissance' technology is a no overall feedback design with a differential circuit that uses only one step of local feedback. This is claimed to result in virtually non-existent intermodulation distortion, and an extremely fast amplifier with no phase errors resulting from feedback. More importantly, with this circuit topology, the speaker cannot send back its counter-reaction after a musical impulse which normally leads to a reduction in clarity of the music, a lack of tonal accuracy, and the feeling of the live performance being lost. The 'Advanced Renaissance' technology is said to include increased frequency extension, articulation, and dynamics in the lower frequency octaves, and is found in all of the MOON power amplifiers.

Another feature of MOON amplifiers design is a custom proprietary toroidal transformer that has a lower magnetic, electrical and thermal loss, resulting in a claimed much better power transfer. Consequently, a lower regulation factor is achieved which basically is saying that the transformer can supply power with only a 6% fluctuation, while you can expect 15% to 20% in common transformers. While I had the i-5 plugged into my PS300 Power Regenerator the entire time, it probably did not make any difference at all. Actually, the transformer in the i-5 probably makes a Power Regenerator redundant, even one of the P300's caliber. As explained by an engineer who works with me, whose work involves him with power regulation at industrial levels, in the case of a power amp it is better to have your power regulated in the DC transformer than in the AC supply coming in. Essentially, you want the power regulated as close to the drivers in the speaker as possible, since each step in the process can introduce impurities. In the case of the i-5, they have indeed brought that regulation as close as I could think possible in conventional amplification.

Amplification class is stated as A/AB, with the first 5 watts in class A. This is fairly typical of most class A/AB amplifiers, and often the bias into class A is less than 1 watt. To put that in perspective, 5 watts will deliver about an average of 81 dB with my fairly inefficient Dynaudio 1.3 Mk II speakers (86 dB/w/m) at a distance of 13'. This means most of my listening is done within the 5 watts of class A operation, including peaks.

I would strongly encourage you to read the Moon i-5 White-paper on their website for more details. It is the best technical paper I have ever seen a manufacturer provide on any product. I think this only happens when the manufacturer really has something to brag about, and with the i-5 they certainly do.

Warranty for all MOON products is 10 years for the original owner . . . quite impressive.

The Sound

In my journeys in this hobby, I have chased various designs and philosophies down rabbit holes. Currently, I am pursuing the thought that the quality of power is much more important than the quantity (as long as clipping does not set in). Also, it seems to me that specs may not tell the whole story. In the end, you have to judge a component with your ears, and while that is subjective, and personal taste will make your findings vary from that of the next person, it is the only way to choose what is right for you.

I compared the i-5 to a NAD 317 integrated and Bryston 4B/PS Audio IV amp/pre combo. To my ears, the Moon i-5 did bring the levels of refinement that may be small in absolute terms, but was definitely an improvement in that direction. At this level in the game, it is only these small levels in improvement that mean the world. Here is what I heard:

On "Afro (freestyle skit)" (Eryka Badu, Baduism, Universal, UD53027), comparing the two integrateds, I found the i-5 to have a much quieter background than the NAD and somewhere between a shade better and the same as the much pricier Bryston. This quieter background resulted in better detail, especially at the 60 dB calibrated listening level. On this CD, there is a lot of low level music, and this is where the Bryston's brawn was able to deliver a little more bass, but not by much. I must admit I was fully expecting this unit to be weak in the lower octaves, and I was floored by what I heard. It was fully capable of competing with the likes of the Bryston in that arena. This aspect of the i-5 certainly eliminates the last valid argument against integrated amps, in my mind.

But, in all honesty, to really appreciate the full extent of the lower frequencies on this CD, you need a dedicated subwoofer, where my trusty Velodyne gladly filled in. Now, to put this all in perspective, I did also listen to this CD with the i-5 and no sub, and enjoyed myself enough to not notice or be concerned with the little bit of bottom extension that was missing. I wish integrateds like these had a variable active crossover built in their preamp sections, as this way I could shuffle off those taxing low frequencies to the sub, and let the amp section shine on in the higher frequencies.

As I had suspected, the refinement in the i-5 was more obvious with a better quality of recording. One of my new reference recordings is "Padlock Blue" (Cootie Stark, Sugarman, Musicmaker, 91002-2). Made with minimalist audiophile recording techniques and high-end gear, this track includes vocal peaks that spike at about 15 dB over the mean. This track is a great test for dynamics, bottom end extension, and detail. The NAD was not as fast on the dynamic peaks and seemed to have more grain or background noise, even though it was also plugged into the P300 Power Regenerator. As a result, I could pick out the individual instruments better with the i-5. The Bryston/PS Audio combo again lay somewhere in between the two integrateds, in terms of lack of grain and background quietness.

Where the i-5 outshone all competition was in what I would call speed. The i-5 delivered the vocal peaks with a naturalness and speed that really made me get up and notice the amp as significantly better than the other two units. I consistently noticed the i-5 was faster on transients on various tracks. Actually, if I were to rely on my memory (which, admittedly is poor), I would say the i-5 is the fastest sounding amp I have ever listened to. I really enjoyed that aspect of its performance and will probably always judge every amp I listen to in future by that additional criteria.

Overall, I was moved by the clean, fast sound of this amp. And when I say ‘sound', I mean that what it seemed to do was to get out of the way and let me enjoy my music.


This is the kind of product that is made with refinement in mind. After all, it probably would be very simple to make an integrated with the same specs for a fraction of the cost. Cost concerns are not what products like this are about, and that is why it is classified as high-end. Close attention is paid to each aspect of the design and choice of components used. It is definitely designed with those who are of a quality over quantity bent. Apart from the popping sounds and the A4 input, I would have no problems heartily recommending this unit. Just do not expect it do drive very low impedances or deliver insane volume levels.

Associated Equipment

Speakers: Dynaudio Contour 1.1; Dynaudio Contour 1.3 Mk II; Triangle Titus XS
Amplifiers: Bryston 4B; NAD 317 (Integrated)
Preamps: PS Audio IV
DVD: Panasonic A320; Pioneer D414
Connectors: Self designed


- Arvind Kohli -

Related to the article above, we recommend the following:

Primer - Amplifiers

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