So the question is which is currently the best dac chip?
The ES9018 has the potential, depending on how it is implemented, including the surrounding support logic.
I set out to understand this a little better and rebuilt and modded 2 ES9018 implementations.
The first one is the Yulong DA8 MkI and the other a dual Sabre32 LKS MH-DA003
The Yulong is a pretty close implementation to the reference design from ESS, out of the box, is a poster child for most of the common complaints directed at this DAC. I call this the "textbook" version of the ES9018, as I describe below, textbooks sometimes leave out some of the important stuff.
I was curious to see if some of these issues can be fixed up and indeed it can.
The main mod was to introduce a low phase noise clock from Crystek, this took care of most of the indistinct flabby bass issues and made the presentation less sterile.
In order to improve the soundstage I added discrete voltage regulators from Belleson, this considerably improved the transient handling especially the definition of the bass transients.
It was interesting to note Yulong added a similar Crystek XO to the DA8 MkII, which came out about 8 months after I made the mod.
The main limitation of the Yulong was the use of low cost SMT components for the analog filter, the ceramic caps and SMT resistors do not make for a good sounding DAC in my opinion.
It leaves no room to make any improvements.
This leads to my point of the dependence on implementation, overall pretty average DAC, very typical of the presentation of the ES9018 and reinforces some of the negative impressions of DS DACs in general.
More details here:
http://www.head-fi.org/t/699772/yulong-a28/195#post_11621683
http://www.head-fi.org/t/673033/review-yulong-audio-sabre-da8-reference-dac/1470
The second attempt with the LKS produced much more desirable results, this is a Dual Sabre32 with a low phase-noise Crystek XO and a galvanically isolated USB input.
Shunt regulators were used fro the analog side with the separate power supplies to the various digital parts of the DAC
Out of the box it was sonically superior to the Yulong DA8 including the one I modded, quite untypical for a Sabre32 DAC, it shared more in common with my R2R DACS like the Schiit Yggy and my Esoteric D10 with Dual TDA1541A .
It is about 10% more expensive than the Yulong when I bought it.
This goes back to increased attention to implementation details yields improved performance with the ES9018.
The basic LKS is overbuilt and the analog stage used quality components like Film Polyproplyene Caps and MELF metal film resistors, these are conventional resistors without the leads for SMT mounting.
Rebuilding the DAC showed me the possibilities on how far the performance of ES9018 can be taken to.
About half of the DAC has been rebuilt starting with the analog stage, the critical I/V opamp was replaced with a discrete unit capable of handling the current from the ES9018 operating in Class-A most of the time.
The I/V resistor was replaced with a precision Vishay metal foil resistor with a 0.05% tolerance, this improves the DC precision to 12bits, most of the common DACs use lower quality components with a tolerance of 1% or worse, this is critical in the ES9018 as the standard implementation requires 2 I/V converters per channel for a 4 in total.
This was vast improvement and has convinced me to stump up for the cash to have of 0.001% resistors custom made, this brings up the precision to 16-17bits.
The USB interface was next, both LKS and Yulong use the interface made by Amanero in Italy, however LKS made available an enhanced version with Crystek low phase noise XOs and a low noise power supply to keep the XO performing to their max potential.
A simple upgrade that moved the sound stage a few steps forward, plus it eliminated most the inconsistent performance we sometimes get from USB Audio, especially the high frequency glare and sterility.
This comes back to the point of implementation, the LKS was better implemented to start with and opened up greater possibilities to improve its default state of implementation.
The heart of the Sabre32 is the Masterclock and PLL reclocker, as my modification of the Yulong showed, a good low phase noise XO will transform the pedestrian sound quality to something quite acceptable.
LKS implemented the DAC in a similar fashion and used a Crystek XO as stock, however LKS implemented a dedicated low noise regulator for the clock and the stock performance was considerably better because of that.
LKS used a regulator than can supply enough power for a miniature Ovenized XO (OCXO), without this foresight on the part of LKS, I would not have been able to take the LKS to the next step.
The Yggy struggles to keep up with the modified LKS. The modifications in themselves improves upon the existing work LKS has done.
In summary it boils to attention to details of the implementation with the ES9018, and I can appreciate why Accuphase and Gryphon have chosen the ES9018 as the basis of their DACs.
More details here:
http://www.head-fi.org/t/745032/lks-audio-mh-da003/15#post_11668439
http://www.head-fi.org/t/745032/lks-audio-mh-da003/60#post_11954317
http://www.head-fi.org/t/745032/lks-audio-mh-da003/195#post_12454476