McIntosh Laboratory MX-136 AV Preamplifier 
Home Theater Preamplifiers AV Preamps
Written by Brian Kahn   
Thursday, 01 May 2008

McIntosh has been nothing short of an American institution in the world of high-end audio for over 50 years. While McIntosh is best known for their stereo gear from the tube era, they have kept their line current with modern components such as music servers and multi-zone audio-video preamps, or “controllers,” as McIntosh calls them. McIntosh’s newest such controller is their MX-136, which at $9,500 (as configured with TM-1 tuner) occupies the top position in the tier of McIntosh AV preamps.

Opening the MX-136, I found that McIntosh eschewed trendiness in favor of tradition. While most of the new A/V preamps I have seen at recent trade shows are small to medium in size, with either TFT screens or multi–line LCD and rows of same-sized buttons. The MX-136 is a full-sized unit with a nine-inch-tall by 17-and-three-quarter-inch-wide faceplate on an 18-and-three-quarter-inch-deep chassis, weighing 31 pounds. I first found the large faceplate to be a bit awkward, but soon came to appreciate its ability to transmit the needed information with elegant simplicity.

As one would expect, the MX-136 is a full-featured AV preamp that can decode Dolby Digital EX, Pro Logic IIx, DTS-ES and NEO:6. In addition to these now-expected audio formats, the MX-136 has unanticipated and welcome assets, such as two balanced audio inputs and a Moving Magnet Phono input. The MX-136 also has a pure analog audio path available for optimum stereo sound quality. The volume control is a digitally controlled unit that ensures that all eight channels track within .5dB.

The MX-136 is no slouch in the video department either, with video up-conversion from composite and S-Video to component and then to HDMI. HDMI video signals up to 1080p can be switched, but not processed. Composite, S-video and component 480i/p signals can be up-converted to 480p, 720p or 1080i signals. 

The faceplate features McIntosh’s traditional black glass framed by silver vertical corner pieces. The glass features silk screening on the reverse side to protect against wear. A large display, which crosses the center section of the faceplate, reads out the sources for inputs A and B flanking the volume, all displayed in McIntosh’s trademark blue hue. To each side of the central display is a trio of traditional silver knobs arranged in an inverse triangle. The knobs to the left select the B input and adjust trim levels; the knobs to the right select the A input, volume and surround mode. The glass panel beneath the main display has backlit indicators, which show the incoming and outgoing signals, as well as the signal format. For example, if an incoming signal is two-channel stereo, only the L and R symbols will light up, a 2.1 signal will cause the “Sub” symbol to light as well, etc. A row of rocker buttons across the bottom selects a variety of functions, including tuning, power and so on. While it sounds complex and looks a bit old-fashioned at first sight, the MX-136’s front panel is extremely easy to use and elegant in its simplicity.

Despite the large size of the back panel, there is very little blank space.  All 11 analog audio inputs and three outputs are accompanied by dedicated composite and S-Video jacks. There are two pairs of balanced inputs, an eight-channel input, balanced and single-ended eight-channel outputs, DB-25 multi-channel output and zone B output. There are also three optical inputs, three coaxial digital inputs, three digital outputs and three antenna inputs. On the video side, there are four HDMI inputs and five component inputs, with one output of each format. In addition to the plethora of inputs and outputs just described, there are various control ports that allow the MX-136 to be controlled by remote keypads and custom control systems, such as Crestron, AMX or Control 4.

I started my MX-136 experience by placing it into my stereo system in a set-up as similar as possible to the one for the McIntosh C-220 stereo preamplifier I recently reviewed. I used Classe’s CDP-202 CD player as a source, feeding the McIntosh through its balanced analog inputs and Krell’s Theater Amplifier Standard for power. Connections were by Cardas’ Golden Presence line and speakers were Martin Logan Summits. The antenna utilized was Magnum Dynalab’s ST-2.

I then transferred the MX-136 to my theater system where it belonged. I was thankful for the four HDMI and five component video inputs, which allowed me to connect all my sources without sacrificing video quality. The MX-136’s limited digital audio inputs, three coax and three optical, proved to be restrictive, as the HDMI inputs on the MX-136 are video-only. While many who are in the know argue that digital audio over HDMI suffers from increased jitter and that a separate digital audio connection provides superior quality, there should be additional digital audio inputs if this is the chosen route. This becomes especially important if you wish to utilize the high-quality DACs in the MX-136 rather than those in your source units. Lastly, not being able to accept audio over HDMI precludes the possibility of accepting a high-resolution multi-channel PCM signal, which is currently only being output over HDMI.

I connected my Marantz DV-9600 DVD player and Toshiba XA2 HD DVD via HDMI. The rest of my sources were connected by component and S-Video. I utilized the MX-136’s up-conversion capabilities, so that I only had to connect my Marantz VP-11S1 projector via HDMI.

Setting up the unit required pressing a button on the front panel to enter the set-up mode. Once in the set-up mode, I was easily able to navigate my way through the menus, renaming the inputs to describe the sources I was actually using. The MX-136 lacks the automatic calibration features found on many popular high-end receivers, as most purchasers of this McIntosh will have the unit professionally installed by their dealer. Nonetheless, I was able to set the unit up quickly, using my trusty and affordable Radio Shack SPL meter.

The McIntosh comes with a comprehensive owner’s manual that does a very good job of spelling out all the various set-up options and what the various choices mean. Even though most people who purchase this unit will have it professionally installed, the manual will be informative for those who are curious about the MX-136’s operation and the technology it contains.

Music and Movies
In order to compare the stereo preamplifier capabilities of the MX-136 to the C-220, I listened to some of the same music I used to review the C-220. Playing the track “Your Latest Trick” from Dire Straits’ Brothers in Arms album (Warner Brothers), I found that the soundstage, when played through the MX-136, was very slightly compressed when compared to the C-220, but still very good, especially in width. Imaging was precise within the soundstage. Mark Knopfler’s vocals were slightly thinner through the MX-136, but still easily recognizable as his. The instruments were clearly portrayed with good detail. However, I found that there was a very slight glare, not uncommon with a good share of solid state gear, on the brass instruments.

I then listened to Peter Gabriel’s album So (Geffen). The track “Don’t Give Up” features a duet with Gabriel and Kate Bush. Bush’s vocals were portrayed with good accuracy, detail and no audible harshness. The MX-136 was again slightly less palpable than the C220, particularly through the midrange, and had a bit of dryness compared to C-220’s tubes, as any purist might expect. Nevertheless, when compared with other high-end AV preamps, it’s easy to hear how the McIntosh is true to its roots. Audiophiles will not be disappointed in the musical reproduction from the MX136, even if it splits its time playing back movie soundtracks.

Before moving to multi-channel audio, I listened to the optional TM-1 AM/FM tuner module. The area that I live in, outside of Los Angeles, is surrounded by foothills that make the clear reception of FM radio signals nearly impossible. I was never able to get a signal that came close to CD quality (as some suggested I might), but the tuner’s sound quality equaled that of any standalone tuner that I have used in this location. The tuner’s performance as far as excluding interference from nearby stations (likely an effect of my location) was extremely good, as was its ability to pick up weak signals. I have no doubt that, in an area with moderately decent radio reception, this tuner unit would be a serious performer for those who still dial in some FM music from time to time.

Multi-channel audio and movies is what the MX-136 was built for and it absolutely shines when used for these purposes.  Watching Pirates of the Caribbean: At World’s End (Buena Vista Home Entertainment) on DVD, I looked at the picture both from running HDMI out of the Marantz DV-9600 and component video (both at 480i), and had the MX-136 compare the signal to HDMI. In the past, with other processors, I have noticed severe artifacts resulting from this conversion. However, with the MX-136, there were no artifacts and the component video converted to HDMI video signal was completely watchable. Comparing the two signals, the pure HDMI signal appeared crisper and with slightly less noise, which I attribute in great part to the quality of the originating signal. The audio performance of the MX-136 with this movie was quite strong. The bass notes of the cannon fire were deep and powerful as expected. The characters’ individual voices were extremely natural and easily discernable throughout the multitude of people talking in the crowded scenes. The MX-136 was able to separate the various sonic cues without being overly analytical and dry.

I first became aware of The Transporter (Twentieth Century Fox Home Entertainment HD DVD) during a recent DTS demo. I never saw the movie until a friend of mine loaned me the HD DVD (yes, I have friends who actually bought HD DVD players, as well as discs) while I was reviewing the MX-136. The Euro-techno music that permeates the film’s soundtrack was never overly harsh or brittle. There is a fight scene in which the lead character storms the antagonist’s house. As with Pirates, it was easy to track individual voices and sonic cues throughout the scene. I noted that the MX-136 does not simply gloss over or beautify every signal it is fed. This film is full of fight scenes and explosions that have many effects dubbed in, some of which are poorly done and easy to identify when listening through the MX-136.

Diana Krall’s multi-channel music album Love Scenes  (DTS DVD-Audio) is full of lush jazz vocals that let the MX-136 really shine. Many AV preamps can do a decent job with movie soundtracks, but multi-channel music can be much more challenging. Krall’s sultry voice on “Peel Me A Grape” was reproduced with an artful blend of liquid smoothness and detail.  The MX-136 did an equally fine job with her voice on “All or Nothing at All,” during which I could close my eyes and come so very close to placing myself in the room with Ms. Krall and her band. Don’t tell Elvis.

The Downside
I was disappointed with McIntosh’s decision to make the HDMI video-only. While I understand that the digital signals that are transmitted via HDMI are allegedly more prone to jitter problems than the same signals transmitted via coaxial cable, it would be nice to have the option. The new high-resolution audio codecs are only transmitted via HDMI. Being unable to accept audio via HDMI precludes the MX-136 being able to be upgraded to decode these codecs. 

Assuming that the new audio codecs are of no interest to you, not being able to use HDMI to accept incoming digital signals leaves the user with only six digital audio inputs. Many of today’s high-end home theaters are going to have more than six sources that could benefit from the MX-136’s DACs and/or decoding.

While most people who will buy the MX-136 will have it professionally set up, there are those of us who like to do it ourselves or may simply want to tweak the settings on occasion. I would like to be able to enter the set-up menu via the remote control. With the MX-136, you must press and hold the set-up button on the unit’s front panel. This can be quite inconvenient when the unit is remotely situated, such as it is in my system.

Lastly, at this price range, many people will expect the latest bells and whistles, such as automated set-up and equalization, HDMI 1.3 support, etc.  Those who need these features will have to look elsewhere. For the majority of us, those features or the lack thereof should not be an impediment to enjoying what the MX-136 has to offer.

The MX-136 is competing with the upper echelon of home theater processors. The McIntosh can accept numerous sources and use them to produce superior sound quality with the currently available audio codecs. A concern with the MX-136 and most other high-end AV preamps is that they cannot accommodate the new audio codecs, except through their 7.1 analog inputs. Some of the processors attempt to circumvent this problem through modular construction and firmware upgradeability, but it remains to be seen if these upgrades will work.

The McIntosh processor lives up to the company reputation of providing excellent audio performance. Video performance is quite good, but not up to the quality of the better standalone processors. The MX-136 is an elegant processor that foregoes having the very latest cutting-edge bells and whistles for solid, easy-to-use performance in both the theater and music arenas.
Manufacturer McIntosh
Model MX-136 AV Preamplifier
Reviewer Brian Kahn

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