Bests & Worsts Reviews from Amazon

I've been using the ART DJPRE II for about four months. Now that I have everything configured, the sound is breathtaking. It rivals other phono preamps costing thousands of dollars. NOTE: Be sure to connect the DJPRE GROUND terminal to your phonograph GROUND terminal via a separate grounding wire (spade lug terminals recommended). Also, be certain your phono is connected to a good earth GROUND. It DOES matter! The real trick to get exceptional sound out of this little gem is to feed it what it likes best... that is a diet of PURE 12 volt DC. For a cost of about $30 you can build your own 12 volt PURE DC power supply. I've posted a picture that shows the details about how to do this. This little simple DIY project also gives you the ability to conveniently turn the unit on/off from the front. This is a feature other reviewers have noticed the DJPRE II is missing and would sure be nice to have. UPDATE Nov 2, 2013: Amazon moved the picture(s) I posted. To see picture(s) click on hyperlink of my reviewer name, then select the tab for "Images," and on that page scroll down and select hyperlink for "Image Gallery." You will find picture(s) and DIY instructions there. Initially, I'll admit I was a little disappointed. While the sound was very good, there was a subtle but yet unmistakable 60 Hz hum that I just couldn't get rid of. All the grounding tricks in the world, and believe me, as a retired military electronics engineer, I know MANY grounding and RF/EMI shielding techniques, I could not eliminate the hum. I just couldn't live with the unwanted noise. The unit's only drawback turns out to be its own supplied power adapter/converter. The unit's operating voltage is spec'd at 9 to 12 volts (AC or DC). The DJPRE II that I received from Amazon was supplied with a 120V AC to 9V AC adapter. NOTE: As of the writing of this review Amazon Product Features says "12V DC (Adapter included)" - a little discrepancy, but no big deal. I tried using other power adapters (I have many). I tried 12V DC, 9V AC (supplied with unit), and just to see how rugged this little dude is, I even tried a 15V DC adapter. The DJPRE II performed about the same, regardless of the power adapter used. That low level but annoying 60Hz hum was there in every instance. I began researching the high end audiophile grade phono preamps costing between $2000 to $7000. Being a technical engineer, I check out the spec's very diligently. I noticed that some of the high-end preamps, although connected to a regular 120V AC wall outlet, actually use an internal relay switch that switches to internal "battery power when operating" and then when not in use, the internal battery is charged by the standard line voltage (converted and rectified to DC of course). After a trip to my local electronics retailer, about $30 in miscellaneous parts, and a little creative ingenuity along with a can of spray paint and my prototype build time, I was ready to try out my theory. I plugged my custom built PURE 12V DC power supply into the DJPRE II and I was instantly transported to musical nirvana (and NO 60 Hz hum)! FURTHER INSIGHT: If you check out the photos I posted, you will see that my system uses a non-resonant Sumiko HS12 headshell mounted with a Lyra Delos MC (moving coil) cartridge, that is fed to an Ortofon Verto step-up transformer where it is converted to the MM (moving magnet) output level required as input for the ART DJPRE II. The ART DJPRE II is NOT able to use a high-end, low voltage (typically .5 mV or less) MC cartridge output directly. The ART DJPRE II is designed for use with MM cartridges, output loading: 47 kOhm / 100 to 200 pF. The output range for MM cartridges is usually somewhere between 4 to 9 mV. I highly recommend this product if you are willing to build a very simple 12V DC power supply. I guarantee you will be amazed at the sound quality that fully complies with RIAA standards. Happy listening to all.