ISL9R8120P2_Q Fairchild Semiconductor Rectifiers
I'm not exactly sure what the replacement part will be, but nice devices.
If you want something exotic, I'd recommend the SiC devices:
Digi-Key - C2D05120A-ND (Manufacturer - C2D05120A)
True. The O2 is so much older and all possible amps for it are completely exhausted at this point. Who knows what new and innovated analog design might come along next for the LCD-2, we need more people on this intractable problem!
How long has this company been around? Would it by definition be FOTM due to this fact alone? Will they survive as long and continually be producing top quality products as say a Krell?
Be careful not to overgeneralize. The order of the distortion as well as how the driver is integrated is very important. Also, you might come to find that other factors are more important than raw harmonic distortion numbers anyways.