2 Ch. Mic Pre + Digital vs. Digital + Pre-amps

[Nick B n Kona]

This is related to a recent thread I posted, but some new territory. Basically I need a good 2 channel mic pre to run into my computer. It's kind of tricky because there are some "Mic amps with digital outs" and some "Digital interfaces" with "good" pre-amps.

I record at 24 - 96 using a Sonar-Branded Edirol (Roland) Computer interface (basically the FA66) that came with a previous version of the soft-ware. I do guitar only, no vocals, with a pair of KSM 141's.

The current I/O lacks gain; the gain must go almost all the way up to get the proper sound and volume from the mics. I'm looking to spend around $500 to get a good sounding unit.

There are several pre-amps that offer digital interfaces:

TC Electronic Konnect 24D $499

Aphex 207 Digital $499

DBX 386 Digital $499

Presonus eureka Pro $499

Or would I be better off with a "Digital I/O" that has better preamps?

M-Audio Firewire 410 or 1814

Any help on this is much appreciated.

Nick