My Modwright/Music Hall CDP had a tube-output stage added using 5687 triodes. They're little guys and add dimension and texture to the music without the "old-school", lush, warm colorations people often associate with tubes. Dan's original-work 9.0SE preamp uses the same tubes to similar but even more profound effect.
I agree that modding for the sake of spending money is silly. It should be targeted at weak points of a particular piece. If you think all the research companies do is designed to achieve peak performance, irrespective of price-point and target market, you're kidding yourself.
There are things you can do: I damp the chassis of CD transports and my tubed preamp using Dynamat and Plasti-Clay. You can build your own speaker spikes and rollerball-isolation pods. There are lots of things you can try yourself at little or no cost. If you like where it goes, great! If not, that's OK too - you're not out anything.
Or you can just assume everything sounds perfect just the way it is - THAT's bliss.