Powerbook (digital audio) and 1/8" jack NOT getting along

Question

ok see if you can help me troubleshoot this.
i bought two of these cables:
<http://www.cablesforless.com/index.asp?PageAction=VIEWPROD&ProdID=2779>
"Our Custom Made 3.5mm Male to 2-Male 1/4 inch phono plugs audio cables are perfect for connecting your speakers and microphones. These cables feature Belden's 1800B digital XLR cable and Steren® precision machined connectors. To ensure maximum signal integrity and protection from RF and electromagnetic interference the cable also features a Beldfoil® shield and fully shielded connectors. Professional termination using high grade solder ensures optimal signal transmission. Designed for optimal sound quality, Belden's performance speaks for itself. Compare Belden's specifications (below) with those of other digital XLR cables and see for yourself how Belden cable is unmatched. Belden Brilliance® teamed with Steren Connectors brings audio to life!"
sounds good, right? they both exhibit the following symptoms.
i'm using it in the headphone jack of my powerbook g4 15" and going out to a little mixer so i can hear system audio, itunes, etc. through my system. this longer cable is replacing a monster cable of the same kind (but shorter).
i'm getting absolutely HORRIBLE buzz when i plug it into the headphone port. if i jiggle it a bit i can get it to behave but only if it sits just right.
on a crt imac and an older titanium powerbook G4 the issue is much better. i still hear a line hum. i wouldn't want to record like this, but it's not a nightmare.
on an ipod plugged into the power adapter it works beautifully. however, i CAN get it to buzz horribly if i jiggle the plug as i insert/remove it.
eyeballing it with the monster cable tip, it looks exactly the same.
so on one hand, the monster cable works great in all uses.
the cablesforless cable works terribly on the powerbook but nowhere else.
now here's a clue: the powerbook G4 has combination analog/digital input and analog/digital output jacks. i haven't been able to repeat it reliably, but the cablesforless cable seems to be able to trigger the digital interface part, as evidenced by a red light shooting out of the port.
unplugging the powerbook totally removes the buzz.
i get the buzz when this cable is in EITHER the input or output jack.
tried a different power supply in a different jack in the same room... same results both ports (slightly different tone to the buzz)
if i remove the little mixer and plug the 1/4" cable ends into two inputs on a practice amp, i get the same issue.
finally, i got another digital audio powerbook g4 15" and the connection seems to be slightly more reliable, but still problematic.
PowerBook G4 Aluminum   Mac OS X (10.4.5)  

Answer 1

For starters, EPUB is a profile of XHTML, not HTML5. Further, audio and video support are part of the recently-approved EPUB3, which the release notes for ADE 1.8 explicitly say is not yet fully supported. Specifically, <epub:trigger> will allow you to use audio and video: http://idpf.org/epub/30/spec/epub30-contentdocs.html#sec-xhtml-epub-trigger
Do these EPUB files that you're not seeing in ADE pass validation? http://validator.idpf.org/
Basically, it sounds like you're trying to do things that ADE isn't supposed to support yet, and in a way it is unlikely to ever support (since ADE is known to be pretty conformant to the EPUB standards, it's very likely it will support the EPUB3 version of doing things rather than the hackery I've seen for Apple's reader).