Have you considered the Aesthetix Calypso preamp? I believe it has both unbalanced and balanced inputs. Other preamps with both kinds of inputs include:
* Atma-Sphere MP-1 and Mp-3
* Audio Research LS-25 MKII
* BAT gear
* EAR 864 (has 1 XLR input I believe)
* Pathos InControl (but I think it only has 1 XLR input)
Personally I like my First Sound preamp but it doesn't have the balanced inputs you seek . . .
* Atma-Sphere MP-1 and Mp-3
* Audio Research LS-25 MKII
* BAT gear
* EAR 864 (has 1 XLR input I believe)
* Pathos InControl (but I think it only has 1 XLR input)
Personally I like my First Sound preamp but it doesn't have the balanced inputs you seek . . .