I don't understand. You say you connect your keyboards to the line ins on the 003 rack. Okay. Then you talk about adding mic pres because you don't like the 003 pres. Fair enough again as they kind of suck. But what exactly do you intend on using the new pres for? Mics or keyboards? If you're using them for mics then to bypass the internal pres you want to hook up to the line ins, but then you lose your keyboard hookup. And are you talking about an 003 rack with 4 line ins or 003 rack+ which has 8 line ins? I know the Motif and Fantom have stereo outputs, not sure about the Virus and microKorg.

With keyboards you don't need or even WANT a preamp - they have plenty of level on their own. All you want is a decent firect box. Radial makes a couple, the best probably being the JDI Duplex Mk4. See this link: [[url=http://[/URL]="http://www.radialen…"]Radial JDI Duplex Mk4 stereo passive direct boxes[/]="http://www.radialen…"]Radial JDI Duplex Mk4 stereo passive direct boxes[/]. Much cheaper solution than what you're proposing. $350 at Sweetwater times 4 for $1500. 4 ADL600 would be $2196 times 4 for $8784. 4 Neve 5012 would be $1895 times 4 for $7588. 4 Focusrite red 8 would be $2400 times 4 for $9600. 4 Summit Audio TPA 200b would be $2500 times 4 for $10000.

if you plan on using a direct box as the above poster suggested, you are GOING TO NEED MIC PRE'S. keys are line level outs, a DI will take the line level out and step it down to mic level, therefore it will be lower in volume and thus needing a mic pre to jack it back up to line level into your recording daw.
i use mic pre's all the time on keys especially tube to make them sound better, my pre's have direct inputs on them already so im good to go. as well as you should.
go withe the pre's if they dont have a DI on them buy a Radial DI (stereo) box and make the sounds you want.