Seventh Circle Audio

Are there options to the Hardy 990c like the SC25s, Forsells, Avedis that would work as well without much modification? Or was the circuit optimized for the 990c?

Thanks!

DUH . . . read the J99 page on the website . . . yes you can substitute! Sorry . . . now anyone who has tried different opamps . . . like the SCA, Avedis or Forsell care to comment if these are different from the Hardys.