I'm re-learning a Bach Gigue right now. I have always found them to be particularly challenging from a technical point of view. The tempo is quick and the texture can be complex, at least for guitar! Here is John Williams playing both the Bourree and the Gigue, which starts at around 1:52:
I haven't played this Gigue for about thirty years, but it seemed to come back into my fingers fairly quickly. Accent on "seemed", because then it bogged down. The usual solution to most technical problems, especially with Bach, is to practice very slowly, which I did, but it still was just not coming together. Then I tried something fairly new for me: practice very, very quietly. It is all about control, after all, and very quiet practice puts all the focus on control. This proved to be the answer. For too many years, ever since a trombonist said I didn't have a strong enough forte on one of my graduation recitals, I have just played the guitar too loud. I'm not alone, a lot of classical guitarists hammer away. But I think I finally shook that demon. These days, you don't have to whale on it, just amplify as needed. The virtues of the classical guitar lie more in the piano end of the spectrum, not the forte... It sounds like Williams is playing loud, but I don't really think he is. If you watch closely while he plays the prelude from this same lute suite, you can see he is very relaxed:
The incisiveness comes from the right hand position, I believe. With a high wrist, the nails are pointed into the strings at a sharper angle. You have to be relaxed to play this prelude--trust me! And I think he is. Also, with a little studio magic, you can punch up the sound as you wish. The one time I heard John Williams in a live concert, he used amplification for both the solo and concerto halves of the program. In conversation afterward, I learned that he has done a lot of research into how to get the best sound when amplifying classical guitar. So I don't think he ever plays heavily--or needs to.