Narrow and Wide jitter adjustment switch settings (affecting SP/DIF and Toslink inputs only): I switched back and forth between the iDecco’s “Narrow” and “Wide” jitter adjustment settings and found the “Narrow” setting gave a clearer and more focused sound. The “Wide” setting has a slightly softened and perhaps more forgiving sound that is appealing in its way, but a sound that also limits the absolute accuracy and vividness of the overall presentation. That said, I could see how the “Wide” setting might be just the ticket when using the iDecco with high-jitter sources.
USB vs. SP/DIF Inputs: Among DACs that provide both USB and SP/DIF inputs, the common wisdom is that the SP/DIF inputs will always sound better than the USB inputs, and in most cases the common wisdom holds true. But frankly, the iDecco DAC really surprised me in that its USB and SP/DIF inputs sounded essentially the same, which is pretty remarkable. I did numerous back-to-back comparisons, first feeding full resolution WAV files via USB to the iDecco, and then playing the same musical content via CDs in my reference disc player and sending the resulting digital audio streams to the iDecco’s SP/DIF inputs. The sonic results were so similar that I couldn’t reliably characterize substantive differences (if any) between them. I’ve never had that happen when comparing USB and SP/DIF inputs in a DAC before. Cool, no?
During my listening tests, I compared the iDecco DAC both to a PS Audio Digital Link III DAC ($995, but currently offered at the special price of $700 in the U.S.) and to the output section of my reference Musical Fidelity kW SACD player (no longer in production, but a very costly player in its day).
I found that the PS Audio DAC produced a subtly sweeter, darker and subtly more “romantic” sound than the iDecco DAC, while the iDecco offeed a more resolved, open and transparent sound with—by comparison—an ever-so-slightly more lightly balanced presentation overall. I also found that the PS Audio DAC’s SP/DIF input sounded better than its USB input, whereas the iDecco’s USB and SP/DIF inputs, as mentioned above, sounded equally good.
In comparison to the DAC/output stage of my Musical Fidelity kW SACD player the iDecco offered many similarities, though I thought the Musical Fidelity offered slightly better resolution of low-level details and low-level dynamic contrasts, and a bit more defined and nuanced bass. On the other hand, you could argue that the iDecco offered a more relaxed presentation. In any event, the sonic differences between the iDecco DAC and the DAC/output section of the Musical Fidelity player were relatively small—especially in light of the big price differential between the products.
Given these results, I’ve come to think that the iDecco’s DAC section alone could more or less justify the product’s entire asking price, which is remarkable when you consider that there is so much more to the iDecco than just its DAC section
SONIC CHARACTER, AMP
Having listened to the iDecco DAC/Preamp sections driving a powerful and accomplished pair of outboard monoblock power amps (the NuForce Reference 9 v.3 SE pair), I felt I was in a pretty good position to assess what the iDecco’s own amplifier section could do by comparison. My conclusion, not too surprisingly, is that the iDecco’s amplifier section is very good for what it is: namely, a high quality, mid-priced and moderately powered amplifier offered as part of an affordable, multifunction integrated amp. But that said, I would also observe that the iDecco amp is not quite the equal of a high-end standalone power amp, nor should we expect it to be.