Nice Tone Change ,But
First great service , ordered in the morning and received my order the next day via Canada Post. I tried a bunch of combinations of the Sovtek and JJ tubes that came with the amp and the upgrade package. The Preferred 12ax7's were a nice improvement ,quieter noise level and warmer woody sound. I didn't care for the Mullard EL84 over the JJ's . The Mullard's break up very fast and sound a bit mushy, you lose some volume too. The stock JJ's have a lot more punch and volume to them. The combination of the new Preferred 12ax7's and the stock JJ EL84's work really well together in this great little amp. It gives you more range of sound , from Blues to a more Modern crunch.