Here's a topic that's never been shy of controversy: is Deryck Cooke's performing version of Mahler's Tenth Symphony valid? Was it even ethical? As many know, Mahler died in 1911 and it was eventually discovered that his Tenth (thought to be left unfinished) was in fact complete in short score. Musicologist Deryck Cooke, I believe in the 60's set about making a "performing edition" of the draft. This was not a case like Mozart's Requiem, where music had to be composed by Sussmayr to complete the work. The music was entirely Mahler's, with no missing bars. Cooke simply orchestrated the draft. But did Cooke have the right to do this? Although the music was complete, Mahler would have significantly re-worked, even re-composed it during orchestration. But, the catch is that Cooke never regarded it as a completion; he knew that only Mahler could complete the work. Rather, it was simply the draft score made performable. Now, as a Mahler fanatic, I wholeheartedly endorse this fascinating "might-have-been." To say that the Tenth should have been buried, unheard, with the draft only available to historians would have been a travesty; this wasn't someone taking preliminary jottings and composing the piece themselves and calling it a completion. The music does not deserve to be buried and forgotten, it deserves to be heard. Although some of the music is obviously lacking the refinement it would have had Mahler lived to complete it, much of it is glorious. As for the orchestration, well, Cooke was no Mahler (in fact, the scoring sometimes sounds too much like an effort to sound "Mahler-like." And that bass clarinet part at the end of the Finale, ugh.), but that's a small price to pay. I think the symphonic repertoire is richer for having this performing edition. Many have begged to differ, including Theodor Adorno, a brilliant cultural critic from the Frankfurt School in the early to mid-20th century. Check out his preface to Mahler: A Musical Physiognomy for a rather vicious rebuke to Cooke's project. At least the Tenth is in no danger of being withdrawn these days. I recommend Simon Rattle's recording of this work with the Berlin Philharmonic. Although I've never really liked the sound of their brass section in any era (too harsh, IMO), the strings are sublime and that wonderfully dissonant nine-note chord at the end of the first movement will give you goose bumps. I understand it's on DVD-A as well.