I used a number of 300B amps before and they do work better with certain tube brand. One common thing I found, however, is that the TJ/Sophia brand (mesh and carbon) is not as reliable. It's actual tube life is also 30% - 40% less than advertised, depending on who you buy from.
Initially I thought I was scammed by independent sellers. However, the most recent pair was purchased at full price from authorized dealer. The tubes tested below weak way before they should be.
The tubes don't hold bias well neither. Every other few days, I would need to re-bias the tubes. Since I used different 300B amps, the issue cannot be the amps themselves.
I have not tried the KR300B. Based on my experience with the 842, I would definitely give it a try.
Just my (incomplete) $0.02.
Initially I thought I was scammed by independent sellers. However, the most recent pair was purchased at full price from authorized dealer. The tubes tested below weak way before they should be.
The tubes don't hold bias well neither. Every other few days, I would need to re-bias the tubes. Since I used different 300B amps, the issue cannot be the amps themselves.
I have not tried the KR300B. Based on my experience with the 842, I would definitely give it a try.
Just my (incomplete) $0.02.