Go to the web page, they show a picture of a discrete front end (surface mount transistors) plus a 4580 opamp!
Discrete front end is a great way to get low noise, but the sound quality (distortion) is unlikely to be as good as a proper opamp. We see discrete front ends in a lot of gear, all the way back to the AD20. It will never sound good for music unless designed by a competent engineer. They are great for video or ambient sound (low) noise, and that is what most (video) people want.
For example, the best sounding recorder I have is the Sony PCM D50. Someone here posted a schematic of the front end, and I saw ADA4841-2 as the opamp. That part is designed to operate at low voltage and low distortion.
Now let's compare that to the Creative EMU 0404 USB. This is an excellent very low noise USB device, with top converters too. The problem is the discrete front end on the mic preamp (four surface mount transistors per channel). This is great for low noise applications (eg., a dynamic mic input, far from the sound source), but it sounds noticeable worse than a TI INA163 instrumentation amp running at +/-15V.
So, after buying, modding, and sometimes ruining tons of gear, I recommend either buying a Sony D50 and putting phantom power in front, or buying an INA163-based preamp and putting analog output into a solid line-level recorder, Edirol R09 or whatever. Save yourself the aggravation of using a cheap mic input...
Note: my comparisons of several interfaces are based on Countryman B3 mics in front of an excellent Meyer PA in a local night club. I've tried numerous recorders including: Fostex FR2-LE, Edirol R4, Edirol UA5, Presonus Firebox, etc. None of them touches the sound quality of an ancient M-audio Duo USB interface with INA163 preamps! The problem is that the convertors are not great on this box. So I may just hack it for a preamp only.
I've been poking around a lot. Older boxes use INA217. Most current gear, such as RME Fireface use TI INA163 Now both Apogee and RME are moving to TI PGA2500, which is a programmable gain version of the INA chips. There are some DIY projects working with the PGA2500, but the problem is you need a digital controller chip to set the gain. The digital and analog parts have to be separated on the board to avoid interference. Programming is also hard. So, my recommendation is to build an INA163 preamp + phantom PSU. Even something with fixed gain, like 20dB, would go a long way to making all of our portable recorders useful.
BTW, if Jon or someone else took this on, I would be interested in buying one.
Richard