But ultimately…does the maths really matter? What does it sound like; or what do you think/believe it sounds like “to you”? Are you happy?
In the same lines as my vet telling me that my cat Zebedee has blood test values of such and such. My concern is solely “will I have a cat at the end of the week”?
I had the best intentions to get to bed early for once and be fit for work, but you had to ruin it 
I think the Technology Connections video does a pretty good job of explaining both the theorem and also the issues that Simon brings up:
It only matters in as far as to get a DAC to sound as accurate or as analogue as possible, it needs to take great care in this reconstruction filter.
This then opens out into a huge field… with different approaches; ie Naim use IIR reconstruction with the cost of phase distortion, but low processing overhead, compared to say Chord who use FIR reconstruction with large filter response kernels (taps) with more accurate phase / transient response at the cost of processing overhead / latency… you pays your money and make your choice… they are all compromises (my original point) so you choose which compromise is preferable to you.
There’s always all kinds of sides to this. A car might only have to get me from A to B but some drivers will have an interest in how things work. Nothing wrong with it. As long as the driving is still fun, I suppose.
I hope Zebedee will be fine! But to pick up this theme, if you are about to choose a high-performance cat that you expect to perform certain functions in a high quality, you might choose to look at the blood test values as well. Though of course you can love any cat that purrs in a way you like.
My take on it anyway
From a theoretical viewpoint, maybe, but ultimately…“are you happy with the the sound as delivered to you?”
Indeed precisely… you pays your money and takes your choice… and in high end Hi-Fi always demo or tryout if you can…
Or try this page… this is really clear and not over simplified… and illustrates the impulse stream issue perfectly, and what the idealised reconstruction must correct for correct analogue reconstruction … which some tutorials on the web completely fail to address… and therefore miss the key considerations…
http://www.dspguide.com/ch3/3.htm
Without understanding this you may well well struggle to understand why digital to analogue reconstruction can only ever be an approximation… and wonder why different digital DAC implementations sound different…
Thanks. I know this is off topic in this thread, but Zebby is having a recurrence of his very serious illness 18 months ago (not unexpected). But thanks to the combined efforts of our local (front line) Vets and the Supervets, he is “stable” as of today.
Wishing you and Zebby best of luck
The Technology Connections video covers the exact same material as on the dspguide page, in a perhaps slightly more digestable format…
Excellent… I think it’s good to understand these things… but I guess I am a little biased in that regard.
I’ll need both, thanks! Will get there …
After cracking N-S I’ll also find out how stereo grooves really work 
Wot, you mean those wiggly lines on “2 oz of plastic with a hole in the middle”?
Every time I put an LP on the Sondek I am amazed at how good it sounds!!!
I was transfixed earlier tonight by the P10 with the new Superline, it’s black magic
Yeah, sod the digits!!!
Personally I think the audiophile culture around DACs is spookily similar to that around cables. Unless a DAC has been very, very badly designed or deliberately engineered to have a coloured sound it will be audibly transparent.
If you were to look at the subjective reviews of DAC’s and CD players over the last 40 some years and put together each time a reviewer claimed the “huge” increase in SQ over the ones reviewed last (month, year, whatever) in a linear line then go back and compare one from the 80s-90s to today’s you would expect the older ones to sound like an Edison cylinder. Not the case, any differences is mostly so minor as to be near inaudible.
Ooooh I need a cartridge and phono stage upgrade…
Round of applause for @Ebor - you called it, 7 hours and 40 posts later, it’s in full flight. Can’t wait to checkout the video link