The Decemberists did it. Loney Dear did it, and so did K'Naan. They all used prerecorded performances to enhance their own live appearances at this year's South by Southwest music conference and festival.
Backing tracks are the anabolic steroids of live music. They add muscle where there otherwise might just be a bunch of humans doing the best they can. And there's no denying that they can make something average sound pretty over-the-top.
When you go to a show and hear prerecorded backing tracks, does it bother you? Would you rather hear the climax of The Decemberists' new record without the children's choir? (It's admittedly nearly impossible to pull off live, since you can't expect a bunch of kids to tour with the band.) Would Loney Dear be less Loney without the pizzicato strings? (They're probably sampled anyway.) Would K'Naan be less K'Naan without the invisible drum ensemble?
For me, it's an old question without an answer. I used to perform my electronic music in the early '80s with sequences I had composed ahead of time on my Atari 1040. It always seemed a bit weird to be in front of an audience and start the song by pressing the letter "A" on my computer to start the first sequence, and then hitting other letters to change reverb settings, randomize the start of other sequenced loops, and so on. I always had this nagging feeling that I was cheating, even though this is the way I made my music.
I seem to remember some story about how the backing track to the Electric Light Orchestra went awry and revealed the man behind the curtain, so to speak. I also remember hearing that fans sued the band for what they viewed as a scam; after all, they came to hear live music and not a good stereo system.
So where do you fall on this? Is it the honesty you seek when you hear a live band, or is it the spectacle you want -- along with whatever it takes to make that happen? Or is it something else?