Katz1,
Sometimes you don't have to do anything major to improve the sound. Changing stock speaker crossover capacitors is one thing that can be done easily and reversed if not satisfied.
My favorite thing about changing capacitors (any capacitor) is listening to them as they break in. At first, new capacitors usually sound horrible. After about 15 minutes they bloom as though someone opened up the door to make things clear, it's really dramatic for me, like someone raised the lights. After that, as they continue to stretch out and break in, the sound continues to get clearer, more subtle and detailed.
Rolling tubes is a little easier, no soldering involved. Different tubes have their own sound. My preamp uses three 12ax7 types in the line stage. I started out with three Telefunkens but it seemed like the sound was over-driven and sometimes too loud. So I changed the first tube to a 5751 (70% of the gain of a 12ax7) thinking I might be over-driving the second stage and the sound became less congested and more subtle. I left the tele in the second position and put a nice low distortion 7025 in the third position to smooth over and finish the sound. Kind of like finishing scotch in a sherry cask. The sound took on a different flavor. That's what rolling tubes is like for me.
I'm not as big of a tinkerer as you might think. Once I like what I hear, I'm done and just enjoy the music. It's only when I get no pleasure from listening that I wonder if it's my ears or the equipment. I can't do much about my ears, so I check the equipment or go to a friend's house to compare.
I do have an extra set of speakers that I might experiment with. They're an extra set of Large Advent's and I'm thinking of removing the internal capacitors and passing the wires to the outside of the cabinet to some terminal strips. That way I can practically change capacitors on the fly till I find my favorite. Then, using another amp, I might "stack" them to see what all the fuss is about.
How's the leg coming along? I can empathize with you're plight because I broke my neck 10 years ago and was stuck in a halo for 3 months. Thank God I had Star Trek recordings to watch, I was so bored. After that, I got hooked on The History and Discovery channels and made it a point to watch all of Clint Eastwood's movies that summer.
One day at a time..each day over is a day closer to getting the cast off.
Good luck.
Rich