Conrad Johnson ET3 preamp. Ate 6922 tubes for breakfast, sounded artificial, and had a tipped up upper midrange with limited bass. It had a great soundstage, though. I struggled with the sound and tubes, more or less due to the huge amount it cost. Then it had those obnoxiously loud and clicky relays that activated every time the volume was changed! That, and I had to occasionally reboot it when the logic board would go bonkers (which it was apt to do every couple of weeks). Got rid of that $3000 piece of junk, and oh so relieved.