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Benefits of an external DAC

I need a sounding board from you folks.  I have a slightly upgraded Oppo 103 CD player that was a big SQ improvement over my Consonance tube CD player.  I need a DAC to take the stream from my iMac, turn into an analogue signal to my preamp.  Lots of folks rave about the benefits of an external DAC so, in progression, I got a Jolida tube DAC, a Schiit Gungnir, and a Channel Island Audio DAC.  I connect the Oppo to the CIA DAC with a coaxial cable.  I input the analogue signal from the Oppo into my preamp with RCA IC's.    

It is easy to switch between DAC in the path vs. the Oppo analogue signal straight into the preamp.  I tell ya, I have done the comparison between all three DAC's vs. the analogue signal run from the Oppo to the preamp and have been unable to discern any difference.   Zero, zip, nada.  I have done the comparison with lots of audio pals and nobody hears a wits worth of difference.

There clearly are lots of devotees using external DAC, but in my system (with a Don Sachs tube preamp, Pass Labs First Watt F5, and Spatial Audio M4 Turbo S speakers, with good cabling), I am perplexed as to why the use of an external DAC makes no difference in the SQ in my system. It sounds exactly the same.  

I am awaiting a demo of a Denafrips Ares DAC to see if this well-regarded DAC does something to the SQ -- one way or another.  So far, the employment of a DAC to improve the SQ of the signal from my Oppo has been an utter waste of time.  What am I missing?
whitestix
roberjerman
4,319 posts
 
Back in the Stone Age Peter Aczel (The Audio Critic) did a comparison test between a Sony Discman and Mike Moffat's Theta DAC. Pre and power amp were Boulder driving Quad 63's. He reported hearing no discernable difference! He postulated that as long as all the CD Redbook criteria were met then ALL Digital to Analog conversion sounds the same - no matter whether the DAC's were multibit or single bit! This is certainly something to ponder, considering today's proliferation of DAC's - some of which are very pricey indeed (Chord's Dave and the Nagra)! After all, present-day DAC's meet the Redbook standards and measure equally well! So if their are differences, what could the X factor be? Jitter, rise time, slew rate, filter anomalies (phase shift)? God (Nyquist) knows!
roberjerman
4,319 posts
 
I bought my first CD player in 1992 because I thought that previous iterations were inadequate compared to good LP playback. I still remain unconvinced of Digital's vaunted superiority over Analog - even though I have listened to many CD's! But I am curious to try out some of today's touted DAC's (DCS, Shiit, Lampizator ... ) to hear if there is any difference compared to a good one-box player.
randy-11
1,913 posts
 
concur on trying the Benchmark DAC3

DACs today are very good and you cannot expect major differences, like with speakers.

Take 2 Aidas and call me in the morning.
helomech
1,706 posts
 
You should be able to discern a difference with the Jolida tube DAC if it's a good design. IME, all solid state DACs sound the same except for extremely minute differences that are probably attributable to psychoacoustics. I finally heard an honest and obvious difference with a Line Magnetic tube DAC. The DAC allows switching between SS and tube output. In SS mode, it sounds like every other SS DAC.
willemj
1,036 posts
 
The tube DAC may be different but is not necessarily superior. Did you measure the frequency response?
CD red book is the product of the largest research effort ever into audio reproduction, by one the worlds best physics labs of the time.
The DAC chips inside these modern external DACs are manufactured by a handful of chip makers, and have now all reached audio perfection at very low cost (they only cost a few dollars each if bought in volume). Implementation is straightforward as long as the DAC designer follows the instructions of the chip maker. Hence I think your observations are what was to be expected. I did a similiar test with a range of different DACs (some very cheap) in a system with Quad 2805 electrostats. I was unable to discern any difference.
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