It really isn't though. The apogee jam Is more than a simple 16-bit 1/4" to USB link that completely relies on the computer for conversion. This is a device analogous to an Mbox 1/2 or m-audio interfaces with some onboard processing. Plus, it's made by apogee, the Mercedes of interfaces - I guarantee you that most of the past top 40 hits in the last ten years were recorded with some sort of apogee processing.
I'm anxiously waiting, wish there was a more professional quality out besides the headphone jack but it looks like something I would use live.
I don't know the technical details of most of this, but I think your a bit mistaken. As far as I know, none of these connection kit devices rely on the computer for conversion. The USB is digital, so all conversion must be in the device, unlike the headphone jack which is analog. The question would be about the quality of the DACs. Bt the Jam, as far as I know, is no better than a cheap Chinese nock-off, Just like some of M-audio, or Mbox's stuff, which also can be cheap even though they make high end stuff.
Apogee's Jam isn't advertising high-end specs, which means .....there are no high end specs
I've go t a LOT of USB audio cable/converters for the iPad that work really well. Some i'll list off:
1) Korg PX5D.
This device is AMAZING. It's a Pandora, but it also is a USB audio interface. It works with the iPad because it has three power modes: Battery/Ac/ USB. The USB doesn't cut it, like a lot of these, but the other modes work. It also utilizes the core-audio driver, which is required for the iPad. rating: ***** out of 5 (that's for the desktop, as you have an editor, which helps DRAMATICALLY, with these tiny things.
2) (not a guitar input) iBasso D4 and D6. These also run on batteries. These use dual Wolfson DACs and sound very good. Rating: *****
3) El-cheapo Chinese, Berhinger knock-off, USB Guitar link thingy. Sounds fine for guitar, no noise (or very low noise). Is the exact same thing as the Berhinger that can be had on Amazon for around $15. Probably as good as the Apoggee (prove me wrong if you can, but only with specs). Rating *** 1/2 (as it's so cheap there MUST be a downside somewhere right?

)
Note: As I mentioned in a post before, this device also has a headphone jack, volume control, high low mode. The Jam just is a simple plug. Now this is interesting. It's possible I suppose, that the Jam is high end and goes by the philosophy 'less is more', and that if it were to offer all the other bells-and whistles, it would be prohibitively expensive. On the other hand, it could be just a rip-off
That's just three. I have more but i'm going to diner
Note: I have two different USB midi cables also. The cheap chinese one I got for about $5 US ( also can be had on Amazon), is very good, and compatible with everything including the iPad. The other one is the highly regarded M-Audio Uno, which has major issues with everything. This is probably due to it being an early version of the UNO, but it's no better than the first one I mention, and it cost 3 times the amount.
When it comes to audio, it pays to look at the chinese stuff these days. If your careful, you can save a fortune and get really quality stuff.
(the saving are HUGE). I have a bit of high end Chinese gear that's very good. Some of these guys are very good at this, and take a lot of pride in their stuff. It just cost a third.