I'd second the "Build it Stock" notion.
Attention to the build quality, wiring routes, good solder joints etc will deliver you an Amp with excellent performance.
There is a time when "the Law of Diminishing Returns" applies. There is an arguement as to just how different % wise a $100 dollar capacitor will sound over a $10 cap. Will it sound 10 times better ? Will it even sound twice as good ?
As Peter Walker (QUAD) said, "if you can hear it, I can measure it".
With my Stereomour, the only thing I have done is change the Tubes to Miniwatt 2A3s from the 50s and a Mullard M8162 for the driver, because I had them in the "old tube box". They do sound better than current Russian or Chinese offerings to my ears, on my speakers and are less microphonic.
I would think some of the greatest changes in the sound of the amp are achieved with a good set of tubes. It may take some time to find, but that's the fun of tube rolling.
I did a similar experiment with the Crack amp. After about a dozen 12AU7 changes from the box I found a Haltron that sounds just perfect and after 5 6080/6AS7 changes , an RCA just excelled. All other parts are absolutely stock, although I did use some cloth covered wire in different colours for the nostalgia.
Maybe obtain a less expensive pair of 45s to set it up and test then move to a premium set when you're sure you're not going to burn them up.
Anyway, that's my 2c worth . The design is what makes it sound the way it does to the greatest extent.
