Krell FPB 700CX

I wonder why Krell went back to using the jumpers, my ksa 300s doesn't have them, but the KSA 250 does. I've never had a problem running a tube preamp with my Krell amp without caps on the input, but I always turn the preamp on a few minutes before the amp. 

@invalid  It may have to do with the protection circuitry. 

If you don't have a blocking capacitor it's a good idea to have some sort of amp and speaker protection circuitry.  Either detect DC and disconnect the inputs and outputs or adjust the bias to compensate. 

Of course, all of this flies in the face of audio purism, so manufacturers have different ideas about whether to incorporate these or not.

My Krell FPB600 ran fine without the jumpers, with Aesthetix Io as preamp, no problem. But turning the preamp and let it stabilize before the amp is good practice.

I check my FPB300cx owners manual and sorry but no instructions given except have the mfg. the work.