Yeah, to address the KT77 issue....

I was disappointed in every KT66 amp I've ever had.  This JTM45, a Dr. Z Rt 66 and so on.  I just don't think that tube has the tone that I am after.  With the JTM, I was thinking 'Marshall' and expecting more of a JMP or JCM tone, which it didn't have.    After swapping in the KT77s and getting them broken in, the amp really became a screamer !!! I love it.  It's has shades of a Superlead, but yet has that warmness of the JTM tone too.

I don't know why I put the SS rec in.... I guess because the harder core Marshalls have SS recs and that's the sound I really like.   It's a cheap experiment.  What ever you do, if you have a Sovtek rec tube, get it the HECK out of there!!  I had two short on me and take out the fuse. One on the JTM and one on a Dr. Z.

If you do go to KT77s, make sure your screen grid resistors are beefed up enough to handle it and you'll have to bias your tubes to about 35-40 mA per side.   I think I had to swap out a bias resistor so I could center the pot ....(if I remember right). 

Wow, we need to work on the smilies here, but anyway, I bought a 18W Ceriatone and a JTM45.  I still have the JTM and it's just an amazing amp compared to Marshall's lame attempt to build a reissue. 

The only thing I didn't like was the KT66 tone.  I ended up swapping out for some JJ KT77s and that is much more to my liking...... more Marshally, if you will.

Nik is a great guy to work with.  He sent me some fresh pre amp tubes after one of them fizzled almost right away ..... it was a Sovtek and didn't surprise me.  I think he now ships with JJs.