See this review:

http://home.comcast.net/~machrone/playertest/playertest.htm

Now, is the testing method sound? Are transistor circuits superior to capacitor circuits when it comes to bass response?

Maybe this post should be moved to General Audio

This post should be in audio hardware, but nevertheless, capacitors are GOOD to have in the input (pre-amplification), but transistors / power transistors right after the output stage make sure that the power outputted is not dependant on the impedance load.

I've seen this link pop up on forums for quite awhile now. If you look at the diagram of a square wave with a highpass of 15 or 20 hz it looks just as distorted as those shown in the diagrams. And that is below human hearing. The diagrams are misleading in that sense- they make the bass rolloff seem more extreme than it actually is on those players.

So scientifically speaking, there should be very little difference in terms of sound quality between the tested DAPs, right?

Also, the author mentioned something about Shuffle having a "fuller" base than the other DAPs and especially the first generation mini. Is that an objective observation?

can only compare it to the other ipod models & yes, the shuffle has a much more "distinct" bass than the others, also the sound q. is vastly superior to the other models. For me, an amazing bargain...

What do you mean by "can only compare it to other iPod models"? What I am trying to ask here is that does the above test mean anything (significant) in terms of sound quality? I believe any differences in sound below (or even around) 20Hz is negligible.

Interesting... Depending on what sort of music you listen to, frequency response at 20 Hz could well be unimportant to you. 20Hz would be an extremely deep bass note. The lowest note on an electric bass guitar is E below low C. This would be about 41 Hz. Frequencies lower than that could well be extraneous (Stage noises, a semi truck going by... who knows). Bottom line: If you consider response at 20 Hz negligible, to you it probably is just that.

For those who like to listen to pipe organ music, 20 Hz can make all the difference in the world.

Do people lose their perception of both the high and the low ends of frequencies as they age or do they only tend to lose their perception of the high end?

If the former is the case, then bass production at 20 Hz will make a lot of difference, but if the latter is the case, then 20 Hz bass production won't matter as much because you wouldn't be able to hear any of it (apparently, our hearing perception degrades the minute we were born)

That's interesting - the couple of times I've plugged into a Shuffle, I actually thought it sounded just as thin/flat as any other iPod I've tried with the EQ shut off. I'm not convinced that there is really as large of a difference as people claim between iPod models - all the ones I have owned have tended to sound pretty much the same through the same pair of Grados.

Hmmm.... I know little about the physiology of hearing (or hearing loss). My point was simply that a lot of music does not include bass notes in the range of 20 Hz. When listening to music of this sort, being able to reproduce what was never there in the first place is, indeed, a negligible factor.

My taste in music is very broad, and I do have recordings with very deep bass. I have far more with nothing below 40 Hz.

When someone says that the ability to reproduce bass down to 20 Hz is of negligible importance to them, I'm not inclined to question.

There are times when response down to 20Hz is important to me, but not often.

Technically speaking, iPod Shuffle is supposed to handle bass much better then the other iPods, because rather than having a capacitor at the output, it has a push-pull transistor network.

But I can't talk about how it really sounds, because I haven't tried an iPod or an iPod Shuffle, nor do I have any interest in doing so.