I can still remember watching the TYA Woodstock set from the balcony of the Alabama Theater - late Friday night movie (before the restoration - they'll have none of this type of thing nowadays!). They and the Who - to me, just stole the event.  I became a gigantic fan of both acts immediately afterward.

The TYA set was impressive, but as far as live recordings go check out the officially released "Ten Years After - Recorded Live" (in Germany, I believe) and the Atlanta Pop Festival/ Isle of Wight LP that was released waaaay back in the 70s.  The latter is a compilation recording featuring 2 - 3 songs of the various bands that played.  The TYA set is worth pursuing by itself.

I'm sure I'll pony-up for the Woodstock recording. 😉 

Recorded Live burns from start to finish. I couldn't get enough TYA during my school years 72-74.

Alvin Lee had this unique phrasing and tone to match.  (IMHO) Unsung Hero

I loved the studio version of I'd Like To Change The World when it was a hit on the radio. The acoustic guitar on this track is top notch. 

Saw the Woodstock film at a theatre in about 1970 I think it was. But that movie had lots of different acts but the Ten Years After portion really rocked out.