In recent years, the integrated amplifier has come of age and has become a contender as a serious audio component. Once considered a very compromised component, a number of companies have sought to change that perception. Toward that end, GamuT has been leading this trend and created the Di150 integrated amplifier, the subject of this review.
The Di150 shares the same understated elegance with the rest of GamuT’s electronics. It reflects the simplicity and functionality that is typical of Scandinavian design. Essentially, the Di150 is a combination of GamuT’s top of the line D3i Dual Mono Preamplifier and a scaled down dual mono version of the D-200i power amplifier making this a true dual mono design. The case is constructed from a thick faceplate made of high-grade aluminum while the top and sides are made from heavy gauge stainless steel and the interior is made from non-magnetic materials.
The large knob at the centre of the front panel window is the volume control. A small light corresponds to the level as you turn the knob either manually or with the remote control. The volume control is an expensive ALPS dual potentiometer. To reduce noise, the manufacturer has chosen a 1kOhm version. This potentiometer cannot make the sound disappear completely, even with the volume control turn to the lowest setting. If complete silence is required, you have to use the mute function.
The volume control is flanked by four push buttons on either side. These are the input selector buttons for CD, Tuner etc. These also can be accessed by the remote control. The remote contains controls for the CD player and other functions. All of these functions are spelled out in the excellently written owners manual.
The rear panel is laid out very well. I generally liked the way the gold plated WBT 5 way speaker terminals are located in the upper left and right corners. I do wish, though, that they were placed a little farther apart so as to better accommodate the heavy speaker wiry with their large spades that the amp is likely to be used with. They are however placed well away from the IEC power cord socket.
Along the rear panel are the aforementioned speaker terminals in addition to two balanced inputs, four RCA inputs for CD, Tuner, Tape and one input marked HTH, which is for use with an outboard processor. Farther along are the balanced output, RCA output and a tape out.
The heart of any pre or power amplifier is the power supply. According to the manufacturer, compared with the original Di150, the Limited Edition has new model output transistors and a refined driver stage.
GamuT has taken a very different approach to their circuit design. The unique GamuT Single MosFet principal is based upon the use of only one output transistor per rail. This is normally seen with low power amplifiers since audio grade complementary transistors are only available in 20 A maximum each. The benefit is that GamuT avoids having 20 transistors on each rail trying to work together. Even when they are closely matched, the remaining differences between them will result in a sound that is affected by phase smearing. Using only one MosFet effectively removes the shortcomings of the traditional multi-transistor output stage.
The MosFet that GamuT uses are an industrial grade NPN MosFet. This means that a complementary PNP is not necessary. Instead, GamuT has implemented the use of NPN MosFets that are identical and are capable of an output of 100 amps, 300 amps peak. This results in an output section without crossover distortion, no emitter resistors and a very low distortion consisting mainly of even order harmonics.
In addition, the GamuT Single MosFet design does not need to use Class A Bias. It is a Class AB design, biased to 14 watt Class A. This is in order to run the transistors at an optimum temperature that results in the best sound.
GamuT also includes NPN Bipolar transistors capable of putting out 25 watts of power which is needed to drive the huge 100 A MosFet NPN output transistors. In addition, the two 500VA Toroidal transformers contribute greatly to the solid sound quality as well and the amplifier’s heft.
All of these innovative circuit designs would amount to nothing if they did not result in excellent sound. In the case of the Di150, these innovative designs have paid off handsomely.
Good recordings are very well served by the Di150. The excellent recording, Aaron Neville, “Warm Your Heart” [ORG-141 45 rpm] is one case in point. The music floats between the speakers with Aaron’s voice located dead centre. The images within the stage are just a bit rounded so as to make them more three-dimensional rather than the sharp edged two-dimensional cutouts that I have often heard. “Everybody Plays the Fool” is one of my favourite cuts on this album. The sound was full and with a bass line that underpins the music. The bass performance of this amp is remarkable. It provides deep, sustained bass when called for.
The new Mobile Fidelity’s 45 rpm release of “Kind of Blue” [MFSL 2-45011] by Miles Davis is the best recording of this music that I have heard to date. Believe me, I have any number of CDs and vinyl pressings of this 1959 classic and as far as I am concerned, this is the definitive one.
The Di150 simply gets out of the way and lets the music come forth with all of the delicate detail and rich timbres in tact. The opening bass line on “So What” is full and weighty but lacks the texture obscuring bloat that I hear with so many other recordings of the same piece. The wide and deep soundstage as well as the transparency that is characteristic of this amp allows you to hear more the room and the micro detail than I have heard from other amplifiers.
Roy Haynes’ “Roy-Alty” [DRY-CD36977] is a good CD to hear percussive dynamics. The drummer, Roy Haynes, is the leader of the group on this recording so, you can believe the drums are front and centre. This amp had no problem reproducing the timbre and impact of the drums while allowing all of the other instrumental lines to be come through clearly.
The sound staging abilities of the Di150 are evident with big band music. The GRP Allstar Big Band [GRP #GRD 9672] is a live recording with a good deal of hall effect detail. The cut “The Sidewinder” utilizes all of the GamuT’s sound staging capabilities. Dynamics are excellent. The big bold brass section is presented with all of the force the band can muster. I thought that I was listening to a much more powerful amplifier. The Di150 can push you back in your seat with ease.
Cassandra Wilson’s “Traveling Miles” [Blue Note – 724385412325] presents her voice from smoky and husky to almost lilting. Her voice is centre stage with the very robust accompaniment of her band all around but the GamuT keeps every line clear and separate, even with the heavy foundation bass lines.
Overall, the sound of the Di150 can be described as clear and slightly warm. It has the ability to float a very tall and wide sound stage with the images well placed throughout the stage. The sound has coherence from top to bottom. No one frequency is emphasized over another giving it a well-balanced sound overall.
This amp also has the distinct ability to seemingly disappear; you are made aware of its presence by how well the music consistently sounds. When present in the recording, the Di150’s transparency is amazing. I cannot recall hearing better in this regard. I listened to many CDs and records during my time with the Di150. Fortunately, the majority of them were well recorded and as a result, I fully enjoyed many hours of listening.
I have a number of audiophile friends who after many years and at great expense, have expressed a desire to simplify their systems and spend more time just enjoying the music. The GamuT Di150 integrated amplifier is a perfect solution. It offers the company’s top of the line preamplifier along with a scaled down (in power output, not quality) power amplifier. With its top-notch sound quality and ease of use, this is a combination with which I could easily live.
I had a chance to compare the Di150 with GamuT’s separate D3i and D-200i pre/power combination. The difference was that the separates had fuller and slightly more extended bass performance. This is not surprising given the D-200’s higher power rating. Understand, the integrated has all of the bass performance the majority of audiophiles will need. If you have to have that last bit of low-end heft, be prepared to lay out another 10K plus the cost of another set of interconnects as the price of admission for the separates. Of course, if brute force power is required, please check out GamuT’s own M-250i monoblocks.
The GamuT Di150 is an excellent product whose sonic performance made the time that I spent with it a real pleasure. For anyone looking for a very high end pre/power amp combination in this price range (US$13,000), I heartily recommend that you get to your nearest dealer and check out the Di150.
Further information: GamuT A/S