I've got a Cal Audio Alpha and also like the GE 5751 tubes. I tried some Sovtek 12AX7LPS tubes several years ago. They sounded good but as soon as I turned the dac off and powered it up the next day, the left tube went dead. I tried another Sovtek 12AX7LPS and had the same results. I blamed this on the 12AX7LPS tube as I have had this dac for many years and rolled many different brands of tubes without ever having the Cal Audio blow out a tube.
