Sounds like you are keeping the amp. I am curious on what the SS rectifier and TAD tubes will sound also. Although I have read from previous post that people prefer the current GT tubes over other brands.
On another note, my SD II 30 is not well yet. Are you around mine area by any chance. I need to A/B my amp with somebody else to see how far off my amp is. If anybody else is in my area with SD II 30, I would like to hear from them. Thanks.
Went back and read your post. Wish I was closer so you could A/B, but it's a good thing you're close to SF. I'm sure they'll get you there.
I played the amp in GC and 9am was loud for me...I bet you could do 10 oclock and get a good sweet spot with a hard hitting drummer...
Also, I spent almost 3 hours with both amps side by side at GC. Same guitar, I just would plug'n'play back and forth. The "Dirty 30" seemed slightly more aggressive, but not louder. The 18 is LOUD...Both are LOUD!! I did not think one was louder than the other, just noticed the 18 seemed to have a more "refined" sound while the 30 had slightly more headroom and seemed a bit brighter and aggressive.
THis was comparing a 18 1x12 and a 30 2x12, so not sure how much that affected it. The 18 did seem to have more thump, but I guessed it was b/c you're only pushing on speaker instead of two and also at a lower wattage.
Be careful, I wrote Budda and asked about it and they recommended against it, said the internal voltages would be too high. If you get a SS rectifier with the proper voltage drop you should be okay, I can't remember off the top of my head how much of a voltage drop a 5U4 tube has...