Man, there are a lot of issues cropping up in this thread based on one simple question. I love it because it was a good excuse to listen tom Who's Next on vinyl and to get out the Kids Are Alright DVD. So, here are a few thoughts on the issues raised.
To the OP, rhymesgalore:
I am sure Febs is right that these are piano notes, without any electric bass notes from Entwistle. I listened several times to my vinyl version, the Polydor 3-record set which has incredible sound and is the definitive collection of Who's Next material. There is no distortion on this version, although I think Febs is also right that Pete is pounding the keys pretty good.
The Polydor set includes the original album as released, the mixes from the first recording session at Studio One in NYC with Kit Lambert producing with engineer Jack Adams on the second, live recordings not released previously from the Young Vic theater in London that was intended as a warm-up for Pete's Lifehouse project, and a few other recordings of music from that era/project.
Oh, and I think Febs may be 3-for-3 because the consensus seems to be that the Danelctro bass never worked out because of string breakage even after Entwistle bought 3 new Danelectro guitars to finish the recording. Several sites say the third time was a charm, others disagree, but one guy says he has the Entiwistle interview where he says he finally gave up and used a Fender Jazz and a less complex solo to get the recording done. Who knows, though.
To E-T:
I don't think there is any bass over those first piano notes in the album recording. Although my turntable doesn't have a time counter on it I tried to listen for the later part you mention at 1:00 (I am kinda old-school when it comes to The Who and don't have anything on CD except Live at Leeds deluxe set and Tommy on DVD-A
). I think the later piano notes and bass notes are overlaid. As I am sure you know, the version of Baba O'Reilly in The Kids Are Alright is a staged "live" version in the Shepperton Studios that was recorded for the movie. In that version, Entwistle plays bass right over the same first piano notes, unlike the original recording. I have the Special Edition DVD, and although it is easy to hear that he does it, there is also a special isolated track version in the extras that just plays the bass track and shows the camera shot on Entwistle for both BO'R and Won't Get Fooled Again. He clearly comes in right over the first piano notes. As to any live discussion of the controversy here, I didn't find anything in TKAA but I didn't watch every scene through.
To Zowie:
I don't really agree that the album was not recorded well on the criteria you mention or any others really. It was recorded by Glyn Johns as Ralph pointed out and the sound quality is really excellent for a rock album from that era. I really think that you need to give a listen to the Polydor vinyl release--the owner of The Analog Room, which is a great record store/cigar lounge in San Jose, CA, dislikes that MCA heavy vinyl version you mention and thinks that this Polydor set has them all beat for SQ and content.
To pds6:
Although I love your avatar, I think that the original version is a regular old grand piano. I don't have that live version at the Albert Hall, but I would assume that they would use an electric piano for a concert where the piano is played live.
Did I get them all? Anyway, thanks again for the excuse to wallow in some Who for awhile.