This is a new experience for me as well. I suppose I should give you less choices *OR* more clearly defined reasons/options. In the past when I have responded to a "how shall I build a linestage?" there has been a bit more noise in the background and even more options.

On caps, I think I got them from RS as well. If you're careful with making sure there is a load, you can get away with 25 volt rated caps. Root2 times 12.6 is less than 25 and an L-C filter with 25 v-in also yields less than 25 volts.

I've worked with two other folks who built regulated PS versions of this line-amp and it took months longer than this. forgive me for getting excited on your behalf.
regards,
Douglas

ask more questions like open ended 'Why?', you'll not upset me.