I see the ladyada wave shield schematic shows a TL072 output amplifier. That's the schematic symbol, but I can't believe that a TL072 will work in that application. Not unless there is some device designated "TL072" that is not the same as the original (30-year old) TI part http://focus.ti.com/lit/ds/symlink/tl071.pdf
If your board actually contained a TL072, then I offer the following observations:1.
The ladyada description does not mention the Op Amp device type, but it says that it is rail-to-rail. The TL072 is definitely not rail-to-rail. No way.2.
The ladyada description says that the Op Amp can supply 100 mA per channel. The TL072 definitely can not supply 100 mA output current. No way.3.
I have not actually tested a TL072 using a single 5V supply, but I have used that family of devices (many, many, many years ago) using +- 12 Volt balanced supplies. I wouldn't expect the TL072 to be very linear with a single +5 volt supply. Not at any output current, let alone at with an output current driving a low impedance speaker or headphone device. No way.4.
I do not have a wave shield to test or to inspect but I have to ask whether you obtained the shield from ladyada (adafruit) or from somewhere else?5.
I would be interested to hear from anyone else who has used this product. What is the marking on the 8-pin audio output device? I mean, there are
dual Op Amps, in that same package with the same pinout, that will operate on a single 5-Volt supply. I'm wondering if the ladyada schematic guy had simply used the '072 Eagle library component and didn't change the value on the schematic to indicate the actual chip used (maybe a TLC2272 or some such thing). I mean, the layout could be OK but the schematic is misleading.
I don't see an actual Bill Of Materials listed anywhere.
(See edited Footnote.)
Now I see a parts list http://www.ladyada.net/make/waveshield/parts.html
, and the part is a TS922, not a TL072. The TS922 looks a little more like what I would expect. (But I find the practice of connecting Op Amps in parallel to be somewhat "creative"---is this really kosher?)
The question is: did your board really have a TL072?[/edit]