DAC "pinch point" in system...

I bought an Xonar U7 for the purpose of hopefully doing crossovers in software on the PC...

Previously tried miniDSP and it crushes the soundstage on the high pass output, so currently running FR into the FR speaker, Bass through the LP of the miniDSP.

DAC source is an Aune T1. Auditioning the U7 to see if it works, NOPE takes something away from the sound the Aune was providing.

The best way I can describe is the Aune paints a wide swath of nicely focused sonic images across the space between my speakers, the U7 pushes everything toward the speakers, leaving a hole in the center. Certainly there's some imaging between the speakers, but it's not even close in spatial detail / focus.

I previously described the HP out of the miniDSP as "sounding like a 70's Technics commercial receiver".

So what's going on? I'm lost - is it coupling capacitors (I assume the U7 has cheap Aluminum electrolytics, as do all such consumer grade DACs) The tube in a Aune? I find that hard to believe...

Any way possible to upgrade this U7 - so I can use it as a multichannel simultaneous software filtered output - or "it is what it is" and nothing can be done?

I feel I'm stuck with the Aune - anything I change or introduce kills my existing nice sound. FWIW I can hear these differences with a 64kbps stream and through 62 year old ears using Daphile and the same convolution filter setup on each DAC. It's the sound stage instrument focus that disappears - something I'm glad I can still enjoy - when its there.
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Sounds to me like the U7 is simply an inferior dac as compared to the Aune. Pushing the sound towards the speakers with a hole in the middle can be caused by various dac design implementation shortcoming IME.

Both the dacs you mention are very low cost. One can reasonably figure a product in a case like that may sell for 3 to 6 times the cost of the parts. That includes the box it came in, the plastic case, any wall wart, included USB cable, etc. If retail price is 5x parts cost, then the total cost for everything that came with the U7 might have been $20. Most of that $20 is likely not for the parts that make the dac work. What do you expect?
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Thanks, guys.

The Jolida "Input Impedance: 47Kohms". Entirely reasonable for any DAC to drive.

The Xonar conveniently switches off the normal outputs when the headphone is plugged in, the Aune does not. I was using that output to drive the miniDSP and assist woofers. So when I noticed the difference, it was just the FR speakers that were playing. Crossover is 60Hz, so the assists only cover an octave down to 30 - certainly not what I'm hearing differently from the rest of the audio band handled by the FR speakers.

Admittedly, the Aune is a better DAC, with it's own +/- voltage power supply, while the U7 is USB powered, no option to power otherwise.

I'm just so surprised an old fart like me can so easily hear these differences, what with 192K / 24 bit and all the modern day technology achievement in both DAC instruments. I'd think my sensitivity would have long been exceeded by the transparency of most anything modern. Glad I have speakers that can reveal such and ears that can hear it.

I have another option coming soon, a Zodio amp with 4 channels of 40W output and DSP built in. If that connects to the PC music source successfully and matches the Aune / JD1301 sound on the high pass - I'll pitch the whole current setup. If not, another $100 roll of the dice with a disappointing outcome - like this U7 -
I'd be suspicious of the phasing - some test tones and measurements would be needed to check this. Personally I wouldn't trust a "gamer" soundcard to be transparent, they could have thrown in some processing to make it sound more "impressive", such as stretching the sound-stage or compression. The Zonar website freely explains that the headphone signal is "enhanced".
Pushing the sound towards the speakers with a hole in the middle can be caused by various dac design implementation shortcoming IME.

My experience also - many times this effect has been caused by opamp rail noise created by classAB OPS switching. Adding caps on the rails to lower their impedance may well bring improvement.
OK, here's what the U7 looks like inside -

(I had written a much nicer reply, but I touched a single key "home" or "pg up" and it all just disappeared)

Build quality of the Aune is better, Wima caps, OPA2134 supporting the Burr-Brown PCM1793. The U7 uses a CS4398. I'd expect both these DAC chips to exceed what I can hear - in all aspects.

Looks like if I want to use the U7 for simultaneous multichannel LP and HP outputs, I'll be replacing at least a couple of caps on the RCA output paths. Who knows what other Al-Els there are in the signal path - besides those decoupling all the other analog outs. This will be a wait and see situation.

I did suspect that there's headphone processing going on, but I'm not running it with the Asus windows driver, which I assume is needed to kick start the C-Media 6632A Sound Processor - I ran it from Daphile, which recognized the card by name, but I assume didnt impart any of the DSP wizardry.



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2005-08-27 4:52 pm
It's all about system synergy.I'm using a xonar u7mkii for and my phantom center image is wonderful. What's the toe in on your speakers. imho that had the biggest impact on the phantom center assuming no phase mismatch anywhere. The 2nd big influence is the phasing of the woofers vs the mids. No capacitor is going to fix whatever you are experiencing.
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