Hello TAS Readers & Editors:
I am posting this comment under D/A Converters because it was spurred by reading the "Further Thoughts - Benchmark DAC1 PRE" article in the October '09 issue of TAS. When Benchmark's own John Siau replies to Alan in the 2nd half, he attempts to explain why Alan found the sound quality of the Rotel CD player / Benchmark DAC1 combo to be only so-so. Insisting that it couldn't be jitter causing the problem, he asserts that it must be due to the transport or CD itself having "non-recoverable read errors (commonly referred to as CU errors)", and/or the transport's "concealment algorithms" which are invoked on-the-fly to repair them.
His assertion raises a big question about the accuracy of CD transports in general. Assuming I have a fairly well-made CD transport (and some clean CDs), HOW BIG of a problem are these CU errors (and the attempts at recovery) typically? In the millions of samples on a given CD track, roughly how many of them end up needing immediate "filling in" (i.e., being fudged) by the transport? My guess is that there shouldn't be enough of them (especially in a first-rate player) to justify explaining why the Benchmark DAC1 would perform less than perfectly with a non-reference-quality CD transport such as the Rotel.
Phil G. - TAS Subscriber