I have the ART DJPre II and Cambridge Audio 551P. The ART is exceptional value, especially with the features it offers, but for sound-quality I would go for the 551P, which in my experience has a more full-bodied sound. There's probably little point in paying the extra for the 651P, unless you want an MC input in the future.[/quote] added 1nF caps to rectifing diodes (even if I would like to test a DC supply, since I guess that those wires (and traces) going/coming to/from the switch, even if twisted, spread some noise Here is a "dashboard" view of how the two perform using 1 kHz tone at 5 millivolts, with A-weighting filtering of the output (making it more perceptually relevant):

Frequency Response: This ranges from 10Hz to 50KHz, with a +/-.5dB tolerance that is enough for the size and functionality of the Pro Audio DJ PRE II. added 1000uF alu-polymer cap on opamp pins (I assume they have the same rails so doesn't matter which one) Also, the distortion should be displayed in the gain mode, not like the built-in ST TS972 where Total harmonic distortion is shown at f = 1 kHz, AV = -1!!!, RL = 10 kΩ is 0.003 % This THD is shown in ideal conditions for CMOS (like any other Op.Amp) since there is no Av=-1 gain and the output load is huge, nowhere near practical application for headphones or studio equipment set of 32,45...90 or 600Ohm (or even for 1k and 2.2 kOhm according to RIAA spec.) This practically means that it is clear why the distorted images are such an expression because 0.003% at 1k becomes 0.03% and when it is amplified 20 times Av=20 ie. 26dB increases to 0.6%, i.e. -44.4dB difference between the carrier tone and its first harmonic. Another added bonus is on this receiver (TX-870), the CD input has a "CD Direct" setting, which allows you to bypass the receiver preamp and associated tone controls. So, if you are in a listening situation when you desire a perfectly flat audio response, just switch to "CD Direct". Otherwise, you can adjust all the tone settings as usual.Finally, let's look at distortion and noise of a 1 kHz tone with 5 millivolt input but without a-weighting: The old AT75E seems to be much the same. I've got one on a 'table that has something like 3 m worth of cable due to previous mods. Add a standard 47k

Because of this, it was incredibly easy to manually adjust it so the two signal strengths roughly matched.G'day all, the ART like many similar designed phono stages uses the 'non inverting op amp voltage stage with gain' approach and whilst that approach works well enough in practical terms the reality is that it cannot provide the intended 'ongoing 6 db/octave rolloff in the treble range required in the original RIAA specification. I looked at the one they suggested from Parts Express, but given that it is made by Mean Well, who to my knowledge only makes switching type supplies (which would introduce a lot of switching noise) I chose instead to build my own ripple filtered & regulated supply. Since this Op.Amp needs to amplify the signal from the turntable whose resistance in the case of the MM head is below 1k Ohm, FET and CMOS solutions with low In in the fA/√Hz range are no advantage, moreover the high resistance at their input increases the thermal noise (Johnson-Nyquist noise). The original wall wart was 9VAC, which is rectified inside the chassis with small SMD diodes in a full wave bridge configuration.

Also, I know these particular stages are budget stages, but why don't the more upmarket ones provide balanced inputs as standard? One gets unnecessary balanced inputs on line stages and domestic power amps, yet unbalanced inputs on the only items where they would be fully justified. I just finished a few modifications on my Art Djpre II, and thought I'd share them with the DIY community. I tried low capacitance cables, which helped a bit, but it still wasn't low enough capacitance to get rid of that resonant peak within my hearing range. Adjust the gain control such that the clipping indication (red) flashes momentarily during the loudest parts of the song. Reduce the gain if the sound is distorted and the led is continually red. The ART DJPRE II is a great bargain here. Other than some strange phase shift at low frequencies and lower input dynamic range, it actually beats the more expensive u-turn Pluto in the rest of the measurements.

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A-weighted signal to noise+distortion ratio ("SINAD") is 83 dB for DJPREE II beating the 80 db for Pluto. Both companies spec 90 dB. When selecting the low-cut filter on DJPRE II, we indeed get a low cut (not as steep as Pluto though) but also a high-cut above 19 kHz or so. Not sure that is a bad thing but it is not what the button says it is doing. For starters, I adjusted the variable output of the ART DJPRE II to match that of u-turn Pluto. This setting was just past the "zero" dial (around +1). This is good as it means the DJPRE II has good range of input sensitivity.