Pacific Valve and Electric Co. Matrix I-Mini modified

I used this little DAC for Headphones and to supply my Jeff Rowland Amplifier stack - awesome! Upgraded to Wyred 4 Sound ... 
NOTE: this is a 110V only device! 
Notes from the Pacific Valve & Electric Co. Site:  
The Matrix Mini-I is a fully balanced DAC with headphone amplifier and volume control. The Matrix Mini-I has SPDIF/BNC inputs, USB,AES and Toslink inputs, single-ended (RCA)  and balanced (XLR) outputs.
Conversion is accomplished through a pair of AD1955 converters that connects to a pair of Burr Brown OPA2134 opamps on output. A separate clock and input receiver is used to keep jitter low as well as a built in up sampler that clocks to 24/192 for the conversion process.   The modification process makes significant power supply and main board components that propels the sound quality.  See "Mod" and "Water Cooler" tab for more information.
The ¼” inch headphone jack on the front takes head phones up to 300 ohms and volume is adjusted on the front volume control.  A push of the knob selects inputs as well as turning the headphone amp on / off and turning the volume control on / off. Matrix Mini Mods The modifications in the Matrix Mini are significant enough to warrant price increase in this model. The modifications take the Matrix from an “ok” Chinese import to a DAC worth about $1000 - $1500 dollars.
In the power supply we replaced the lower cost PN junction diodes with ultra fast, low voltage drop,soft recovery Schottky diodes. While there is a little real estate in the power supply for the changes that the Schottky requires, we managed to sneak in the necessary Vishay BC capacitors (different values, increased tolerances) and resistor circuit changes to support the new Schottky(s).
The upgraded Rubycon ZA capacitors were used in the DAC circuit which extended the low end response and gives the DAC its signature “bloom” in the deep low end, mid bass and midrange. The Rubycon ZA capacitors were also used in the headphone Amplifier circuit and pushed the headphone section’s overall performance
Lastly, a 0.3ppm TCXO was installed in place of the lower cost stock 1ppm. The native clock chip was an inexpensive model and detracted from giving this DAC any imaging or soundstage capability. With the super fast 0.3ppm (a clock found in many expensive DACs), the Matrix Mini modified can be used in an above average audiophile system that is capable of detail and depth retrieval. Bass: Deep dynamic bass with considerable kick and slam. Outstanding dynamics add to the bass response for an impressive presentation.
Mids: Expect a solid state rendition of the mid range with a slightly hot presentation. See "Water Cooler" talk for more information. In lius of all this, the midrange was detailed yet non irritating or fatiguing.
Dynamics: Outstanding. Shakes the room on jazz band and rock music. On orchestras, harps and violins emerge from a dead quite background as do subtle percussion instruments.
Air around instruments: Average for a solid state DAC at this price point.
Body and Weight: Excels at giving an actor body for this price point. You can easily pick out an actor in the sound stage and then focus on the actor's attributes.
Warm/Cold: Moves more to the cold side as do most main stream solid state DAC
Imaging / Sound Stage: Surprisingly good imaging from a DAC at this price point. Threw actors to the left and right of the speaker as well as have them emerge from the back.
Resolution / Detail: Above average detail. This DAC, in no way sounds veiled or cloudy.
Value: Competes with current market DACs at the $1000 - $1500 range. Once broken in, capable of great value. Please note our caveats and see "Water Cooler" talk for more information. RCA Output Level: 0V~ 2.0V adjustable Balanced Output Level: 0V~ 4.0V adjustable (XLR :1=GND, 2=HOT, 3=COLD) Frequency response: 20Hz~20KHz SNR: 105 dB Dynamic Range: 108 dB Distortion : <0.0002%(1KHz) The Matrix Mini Modified was evaluated using CyberServer, Aune Cyclone Transport, Lite CD 21 transport, Aune S1 Music Server, Ming Da MD 75 Amp, Ming Da MC 3008-C Amp, Bada 225 Amp, Doge 8 Preamp, YS Audio SE Preamp, B&W matrix 801 speakers, Magnepan MG III, Magnepan 1.6, Quad ESL 57 speakers, Quad ELS 63 Speakers, Proac Response 2 s, Vandersteen IIC speakers, Von Schweikert VR-2,VR-4 , Harbeth, ZU and Horne Shoppe Horns.
** These notes assume that the volume control is on the 0db position, in other words, the volume function is turned off. ** We want to start out by saying that the modified version is not an upgrade to the Matrix Mini, on the contrary, it is turned into a completely different sounding DAC reminiscent of current "Class B" DACS. There is good stuff and just "ok" stuff, depending upon your system and sound likes / dislikes.
First the good stuff. Unlike the previous Matrix, the bass response, bass dynamics and overall tone is downright breathtaking. If your speakers are weak in this area, then please consider this DAC as it will quickly rectify the situation. On just about every bass recording, not only did it respond with great tones, but dynamics and imaging to boot. If you like rock music, jazz big bands etc., then this is the DAC for you. Keep in mind, that we are not talking about mud, but good clean bass stuff. The bass show continued into the mid to mid bass where male vocals had body, excellent tonal balance (they sounded like males) and imaging.
The next good stuff was the imaging and body. The Matrix was able to move actors (instruments and vocalists) to the left and right of the speaker and render instruments in the back (studio or orchestra hall). We felt that this was above average for a DAC in this price range.
And now the stuff that some panel members raised an eyebrow on; the Matrix is a little hot in the midrange and upper midrange that is reminiscent of the some DACs out there that are benchmarks (get it?). We realize that there are some audio geeks that like this sound. It did not, however, cross the line with glaze or arcing in the upper registers. So it does not become fatiguing during long listening sessions. The Lite DAC 83, it is not, a $1000 DAC it is. The Matrix Mini modified takes a desert experience to warm up and sound right (3 weeks of continual playing). Otherwise, it sounds grainy and flat. The 30 day return on the Matrix has been extended to 60 days.