I have been a user of core sounds' stealth muicrophones on my Sony M1 DAT recorder- they are excellent mikes IMHO. Core sounds has now come out with this CF card that will convert a PDA (hopefully, the Axim too !) inot a DAT recorder;
Here are excerpts from their site:
http://www.core-sound.com/HighResRecorderNews.html#NEWS
PDAudio-CF Interface Card (Hardware)
Using PDAudio-CF, the recorder will be able to record in both single channel and dual channel modes, with sixteen, eighteen, twenty or twenty-four bit word widths, and data rates from 32 KiloSamples/second up to 192 KS/s (32, 44.1, 48, 88.2, 96, 176.4 and 192 KS/s). (Note that even though the PDAudio-CF supports sampling rates to 192 KS/s, some PDAs currently only support sampling rates to 96 KS/s. Almost all desktop and laptop PCs will support 192 KS/s.)
At 96 KS/s PDAudio-CF draws only 45 mA and so has minimal impact on your PDA's operating time per battery charge. (Various models of iPAQs are available with 1000, 1400 and 2200 mAh battery packs, and some of the CF/PC Card expansion packs provide still more battery capacity).
It has two LED indicators, both under software control. One is typically used to indicate that it's seeing a valid S/PDIF data stream and the other to indicate other record system status. Both LEDs can be flashed at various rates to signal sample rate, media-fullness warnings and other information.
PDAudio-CF will accept digital audio data from a wide variety of outboard units, essentially any device that uses an S/PDIF coaxial or optical interface. These include microphone pre-amplifiers/A-to-D convertors (e.g., our Mic2496, Lunatec's V3, M-Audio's Duo), CD players/recorders, DAT players/recorders, hard disk recorders (like the Alesis Masterlink), and digital PC & Mac sound cards. Input is via a 3.5mm (1/8-inch) jack for both optical and coaxial S/PDIF input, selectable via software.
In a laptop/desktop-based recorder, PDAudio-CF will provide a bit-for-bit accurate S/PDIF interface at up to 192 KS/s for use with most popular audio software applications. A WDM driver for Windows XP (SP1) and Windows 2000 is included.