I once used a REF1 with my Krell 600c with no problems and without the DC block. I wasn't very impressed with the sound of the original REF1 but that was a long time ago. I have never had a problem using my amp with a tube pre but would be careful if not adding the DC blocking capactors. Early BAT preamps were known to leak DC.
Feed back on ARC Ref II Tube Pre with Krell Amps
I am looking for first hand experience with pairing a Audio Research Ref II Tube pre amp with Krell 450MCX mono blocks. I know the krells need to be modified to work with tube pre amps because of a potential DC problem, but I am most concerned with how this combination sounds. If anyone has this type of setup or just using a tube pre with krell amps please let me know what you think. Thanks in advance.