Available as an assembled Module and as a DIY project.
This Module is currently available.
500 series Class A mic pre
http://www.audiomaintenance.com/acatalog/aml-17-038_extended_info.html
Included in 87 Racks, 25 are public:
AML ez1073-pre$570.90
AML ez1073-pre$476.24
AML ez1073-pre with Addon EQ - 500
AML ez1073-pre EQ Combo