As good as it gets

after 400 hours everything in the audio chain is fully broken in. the 5-10% won't change your general impression of the amp but it always sounds a little better and less stiff after burn in.
you should swap to nos tubes which sounds much better than the modern chinese/russian crap and tune it to your liking.what tubes types are in there? anything nos 60's made is amazing compared to stock but each brand has their own voicing.

miller,

I’m no expert, but don’t designers create their products around the sound of a particular tube?

Hmmm...

I would hope anything should sound good, and near what your expecting,pretty much right out of the box?

You ears either like what their hearing, or not. If not, move to the next choice?

I guess that's a ridiculous premise.