As some of you may have seen I purchased new to me BHK Preamp and BHK 250. I picked it over my Mac MAC7200. To me it just sounded right, if that makes sense. The other night I was listening and the house was very quiet and I turned off the source and I could hear a very slight noise. I put my ear to the speaker and it sounded like a fan off in the distances. Very low, I can unplug the XLR cables from the 250 and dead quiet. Plug the XLR cables back in, unplug all sources and still there, tried two sets of 12AU7 and the sound doesn’t change. The more I increase the volume the louder the sound and you can hear it a few feet away, but an normal listening levels you have to get right up on the speaker. I ever heard anything noise from the MAC, but it 100% solid state where the BHK has tubes. Other tube equipment I have had all have more noise then this with no source playing. You can never hear any noise when a source is playing, I just wonder if this is normal. If so I can go on with my life and be happy, if not please let me know and I will contact TMR and see if they can send to PS Audio for repair.