This post marks a departure from my general reviewing style. Normally I get a new piece of gear, burn it in, listen to it, dismantle it for pictures, listen to it again, compare it to competitors, listen some more, etc. until I have a complete understanding of how it performs. Then I write up a detailed review and post it. The process generally takes at least a month or two depending on the complexity of the equipment. Meanwhile, people are sending me PMs asking about the device, and the more time I spend chatting with people about it (which I love to do) the longer it takes to finish the review. Taking some cues from my friend Average_Joe, and to a lesser extent 6moons.com, I’m trying a new format: posting initial info and impressions early on, and then incrementally adding more until I have a complete review. So with that in mind, I present the Matrix Quattro amplifier.
I got my Quattro system (DAC and matching amp, XLR cables, and balanced headphone adapter for the amp section) from Jeffrey Tam - Jeffrey is an excellent seller - very helpful, very trustworthy, and very fast with shipping. He has proven himself time and again, and I wouldn't purchase a Matrix product from anyone else. Someone else will eventually pop up on eBay selling the Quattro gear for a few dollars less, but in my opinion it isn't worth the risk to buy from an inferior seller. Plus Jeffrey throws in extras and has options like the cables which nobody else has. I just can't recommend him highly enough.
The amp sells for $399 with shipping included. It ships in what appears to be the same style box as the DAC. The result is the same - well packed with no shipping damage. Inside we find the amp itself, a basic power cable, a user manual, and the remote if you chose that option ($5 extra).
The manual covers both the Quattro DAC and the Quattro amp.
The remote is the same for both Quattro products – when ordering them both, you really only need one remote. This is the same remote used with the latest Matrix Mini-I DAC.
The Quattro amp is strikingly similar to the Quattro DAC in appearance; they were obviously made to complement each other. That being the case, the design is suitably low key that either one could easily integrate into a system with components from other brands.
The amp is fairly basic as far as functionality. There are two sets of inputs - balanced XLR and single ended RCA. Selection between the two is accomplished by pushing the front panel button labeled "source". Up front, we find a pair of headphone jacks. These can be used as standard headphone jacks powering two sets of headphones, or they can be used for balanced operation for a single pair of headphones.
Since the outputs are standard 1/4" jacks, the traditional balanced connections (4-pin XLR or dual 3-pin XLR) do not work here. Instead, this amp requires the use of special cables or adapters. I personally ordered an adapter that allows 4-pin XLR balanced cables to interface with this amp. I'll post some pictures and pricing of the various cable options later in the post.
This amp has remote control capability. A switch on the rear panel controls this feature, and the actual implementation is done through a motorized Alps potentiometer. As with the Quattro DAC, volume adjustment takes place in the analog domain rather than digital.
Jeffrey Tam described the Quattro amp as basically being two Matrix M-Stage amps put together for balanced operation. As far as I can tell that is an accurate description. It has the same opamp input stage and class-A diamond buffer output stage, but everything is doubled for balanced operation. It actually has a total of 5 opamps: one dual channel opamp for single ended use, and four mono opamps for balanced operation. In stock form the single ended path has an OPA2604AP and the balanced path uses quad OPA604AP chips. Since the OPA2604 is just the dual channel version of the OPA604, both paths should be equal in that aspect.
All opamps are in sockets so they can be easily swapped. The implications of this are obvious - as with the Matrix M-Stage, Quattro users will be able to switch to various opamps to refine the sound to their liking. The stock opamps are already very respectable though. I recall them being particularly popular with folks modifying/upgrading amplifiers like the Quad 405. For $399 shipped I don't expect to find a bunch of expensive opamps like OPA627 already included, but the user if free to try those later if desired. I might go down that road myself eventually.
When used strictly in single ended mode, the Quattro is theoretically very similar to the M-Stage. There are a a few tweaks in the general design, and of course the stock opamps are different (with the OPA2604 probably being superior to the OPA2134 in the M-Stage). Aside from that the differences mostly come down to different choices for things like capacitors, volume pot, and toroidal transformer. Whether or not those make a big difference in single ended mode is something I intend to find out by direct comparison to my M-Stage.
The Quattro amp has a pleasing appearance and seemingly high quality construction. It isn’t flashy but it has an understated appeal to it. Aside from the labeling and input/output indicators, it appears identical to the Quattro DAC.
The Quattro DAC features a balanced output to connect to the balanced input of the Quattro amp. Obviously cables are required to link the two units. Jeffrey at TamAudio sells an excellent pair of Palics Silver Net XLR cables (they go by Palic and Pailiccs, same company) that are perfect for the task. They are shorter than usual, so they work well in my situation, and really minimize cable clutter. I imagine they wouldn't work for someone who has the DAC and amp backing up against a wall though. In any case, the cables sell for $100, but Jeffrey is bundling them for free with certain Quattro purchases. Initially they would come free for those who ordered both DAC and amp together. But now I notice this post http://tamaudio.com/blog/?p=433 which says the cables will be included free just for ordering the DAC. I don't know how long this offer will last so if you are interested you might ask.
On the other side of things, you also need a balanced cable for your headphones if you want to take advantage of balanced mode. To that end, Jeffrey makes converters to allow traditional 4-pin XLR or dual 3-pin XLR equipped headphones to interface with the dual 1/4" TRS jacks on the Quattro amp. I got the model that works with 4-Pin XLR cables, and sells for $90. Jeffrey did say he was considering offering a discount for people who buy the amp and adapter, but I don't think that is fully decided yet. The prices on the other items are:
Dual 3-pin XLR to Quattro style balanced adapter: $100
Full custom cable for Sennheiser HD580/600/650: $120
Full custom cable for Sennheiser HD800: $250
Full custom cable for AKG K702/K271: $120
A few comments about those - The Sennheiser HD600 cable seems like a very good deal. Nice aftermarket balanced HD600-type cables are usually over $100 to start with (mine was about $180) so adding the appropriate adapter for Quattro would be significantly more expensive. You might as well buy the whole cable unless you already have one like I did. I'm told the HD800 cable costs more because the unique connectors are expensive and difficult to obtain. And the AKG K702 cable is not exactly a true balanced setup. The cable enters on the side and then shares a single ended connection from one side to the other (which runs through the headband). Jeffrey said he is offering this cable to allow K702 owners a low budget method to tap into the full balanced power of the Quattro amp (output is doubled in balanced mode). This is similar to the Stefan Audio Art E-series cable that they used to sell for $350, or maybe still do.
Hard to read but it says something like "Teflon dialectric MCC copper audio interconnect A5
Comparison to a basic Monoprice Premier cable - the Palics is much nicer looking
I don't have much time spent on the Quattro amp at this point. I burned it in for about 2 weeks solid, and have had a few short listens. So far it sounds excellent, reminding me somewhat of a refined Matrix M-Stage (as it should). Balanced mode seems especially appealing, allowing my HD600 and custom Orthos in an HD600 shell both to produce beautiful music. The Orthos are particularly difficult to drive, but the balanced Quattro seems easily up to the task. It seems to have similar characteristics as the Quattro DAC itself: neutral, detailed, free of grain, and with a very solid bottom end. I didn't immediately jump out of my seat when moving from the built in amp section of the DAC to the dedicated stand-alone amp, but that's to be expected as the integrated amp is quite good on its own. I do think I hear subtle improvements though, of the type that will more fully reveal themselves upon further listening. And balanced mode seems to be a fairly significant improvement over single ended, taking you that much higher over the integrated amp experience.
Unfortunately I'll have to refrain from any further comments on sound until I get more listening time with it. Suffice to say that I am very impressed. The $150 price increase over the M-Stage does in fact seem well justified, and this might just be my new favorite "budget" amp. I don't know where exactly the cutoff is for calling something "budget", but I'd say this probably squeaks in.
As I mentioned, I'll be continually updating this thread as well as the matching thread for the DAC which is located HERE
I often get the question "how well does this amp do with the LCD-2?" I was finally able to borrow an LCD-2 and am updating all my threads with my thoughts on the matter.
The LCD-2 sounds pretty good straight from the Quattro DAC but even better from the Quattro amp. For a relatively low priced amp, it does a good job of delivering the core sound of the LCD-2. Higher end amps can obviously take them farther but the Quattro is a good start. Once again I find it to be a bit better than my Matrix M-Stage. This is surprising because they should be very similar in single ended mode.
I suspect that the Quattro amp would be even better in balanced mode since it would double the power. This could easily be achieved. Audeze sells a balanced cable for $80 and the adapter from Tamaudio is $90 so the total investment is not terrible (although at some point I expect JTam will offer a dedicated LCD-2 upgrade cable, just guessing). At that point you would have spent under $600 for the amp and cables: I don't know a lot of sub-$600 amps that have a great reputation with the LCD-2 and fully balanced is even more rare (I can't think of another at the moment).
Building a system around the LCD-2 using the Quattro setup seems like a great way to go. A budget of $2500 would get you both Quattro units, the LCD-2, and still leave you some left over for a Squeezebox Touch or other source. You could easily blow a huge chunk of that budget on a more expensive DAC or amp, forcing you to settle for just a "decent" headphone like an HD650 or something. So once again I'm really impressed with Matrix.
Edited by project86 - 8/28/11 at 9:42am