Favorite 300B: Sophia vs KR

I ordered 4 Shuguang Treasures for my amp. Pricey but grade b tubes came to $700 for the four. This is the down side to 300b amps is that a) the tubes do make a significant difference and b) you pay almost as much as the amp for good tubes. My new amp is a Mactone so a little more than the the price of tubes but seems to be all about the quality of the tubes with 300b amps. Will be interesting to see if the quality tubes make as good a difference with my push pull setup as they did when I upgraded tubes for my 300b set.

Ladavid,
If you find the time, I would appreciate you posting your thoughts on these tubes in the PP amp compared to use in your SET amp. I agree 300b tubes are`nt cheap but they outlast most pentode type tubes and IMO sound better if the amp is up to snuff.

Two more things about 300bs:

1. by all accounts these new Treasures take a ton of hours to break in - like don't even listen seriously for 100 hours so Charles1's dad might be a bit before I am back but this is my intent. Hoping the upgraded tubes sees the amp jump forward in significant ways

2. counter intuitive one is that I swapped out my high efficiency Audio Note E's for low efficiency Ellis 1801's and the Ellis' just sing with this amp and the EH tubes. Almost like the Audio Notes are too revealing of the flaws in the 300b tubes...so would I expect the opposite in that I might not notice much difference with the Treasures on the 83db Ellis' but should be a wow with the Audio Notes. Curious.

"so would I expect the opposite in that I might not notice much difference with the Treasures on the 83db Ellis' but should be a wow with the Audio Notes. Curious.”

That’s a distinct possibility. A more revealing speaker should be more revealing of upstream improvements.

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.