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.

What tube preamp are you going to use with the Krell amplifier?

Appreciate your question, but the answer I am looking for is what jumpers JMP1? Is needed to put capacitors in path to potentially protect against DC. SS or Tube may or may not leak DC, that's not the question, however.

but the answer I am looking for is what jumpers JMP1? Is needed to put capacitors in path to potentially protect against DC.

Yes.

@imhififan Thank you sir and thank you to all who kindly replied.

@ossidian5 You're welcome! You can engage the coupling capacitors by removing the jumpers.

While almost any tube preamp can be safely used with a Krell power amp without the use of the input coupling capacitors mentioned above, some vintage/boutique PIO (oil in paper) caps in tube preamps tend to leak DC over time and can damage downstream components!

@ossidian5  the reason I asked what tube preamp you have is because some tube preamps are transformer coupled which would be the ultimate DC protection.