Hello!
I had built my S3X 3.0 + C4S during the Covid days. The left tube always had a faint hiss. So I finally replaced the tube with one I brought separately. I re-measured the voltages afterwards. OA is still good ~ 69 V, OB is now higher ~ 86 V. While both are still in range, I wonder if I should put in a matched pair of tubes instead? The amp still works and sounds great (no hiss though!) .. But OB being close to the edge is a tad worrying.. Is it a problem?
Rgds,
Atul