Lemme tell ya a little story about ears...
As I sometimes like to point out, I did my first overdub recording in 1962. I was a kid, then, but deeply into audio, hi fi, and electronics.
But life intervened... I discovered girls (thank you, God!), I discovered life, I went to college, I became a hippie. I learned to play guitar. I lived, I loved, I did a lot of things I can't quite remember clearly. And I barely did anything more than occasionally sit in behind one of the era's live boards.
When, around '77 or so, I decided to buy a tape recorder again (my beloved Sony deck had long since been stolen one dismal day along with my guitar and 300 LPs) I found myself contemplating what I had always considered an abominatoin: a stereo cassette deck.
I hadn't been in a stereo store in a long time (I was running an old Williamson tube amp and a pair of huge folded horn speakers) and I found myself in one of the big name stereo discounters (they came, they went -- I think it might have been Federated).
So, I'm in the showroom.
I'm there specifically to look at a Teac deck on sale for a couple days at $130, a good price for the deck, for sure, even though, as you know $130 back then was a chunk of change -- almost a month's rent in my tiny beachside apartment.
So the shiny-suit salesman is working me...
He shows me the Teac and I'm ready to buy -- but he says, wait, don't you think you ought to see what else we have in the same general range?
I'm suspicious but, you know, I'm a wise guy, so I say, yuh, sure.
So we're looking at some house brand for about $40 more. And it's pretty sleek looking, all right.
He says, let's hear it, OK? I'll use the same tape so you can see the difference between the units.
And he pops the tape in and it's like -- wow -- big difference. The highs are bright and clean and sharply detailed... it's like bright sunshine.
And I'm mentally counting my checkbook balance, thinking, yeah, I could do this.
And suddenly I think -- WAIT! Stop a second, this is classic bait and switch behavior. There's gotta be a catch.
So I study the faceplates for a second and notice this little switch on both for Dolby (B) noise reduction.
Sure enough, Dolby' is
on on the Teac and off on the house brand.
I say, let's make this a
fair comparison, why don't we? And I switch the house brand's Dolby on -- it's immediately much duller. It sounds about the same or a little
worse than the Teac, right off the top.
The salesman says, oh yeah, but you'll never use that... it makes everything dull.
Now, obviously, this situation was
very different -- it's not even an analogous situation -- but it does show you how even a pretty savvy guy can come right up to the brink of being taken -- and I use it to point out one very important thing:
Subjective, situational judgements are
just that. The ears can be fooled and can be used to fool you.
Anyhow -- if we want to talk about
measurable science, you will find that all
responsible parties will agree that external clocking tends to increase jitter.
It's easy to understand how that would happen, since asking a converter to synchronize to an external clock source
does not take that converter's internal clock out of the picture -- it makes the internal clock work harder to continually adjust itself to the incoming clock source -- and
that will always tend to increase interstitial timing inaccuracy in a given externally-clocked converter-- jitter, IOW.
You might
like the sound better -- and that's fine. (With me, anyhow.)
As Apogee's Max Gutnick will assert: Apogee's testing shows a significant number of people hearing a converter using a Big Ben for externally clocking say it
sounds more accurate to them. (And if I'm mistrepresenting him, here, I hope he will correct me.)
But if there
is a real difference in sound, it is likely at least in part to be the result of
increased jitter in AD conversion.