pachelbel's canon
If you are talking about the episode called Dark Passge, the song at the beginning is 'Catching Up' by Orange, the same band that did the theme song for it.
implosionatic - hot hot heat
The song Ryuubi sang near the end of episode 12 of Shin Koihime Musou is not the same song as the one that was in the beginning of the episode. The song she sang was the first song that the Chou sisters ever sang. I have tried to find out what it is called , but I ended up wasting my whole afternoon.
The song played at the beginning of the episode is "Inta Hayati" by Samir. A credit at the end notes hims as "vocal and lyrics."
This Is Christmas by curtsmith
pachelbel's canon
The song is called How soon is now by the smiths
There's been dispute on what the song/artist was in the beginning of that episode. It was speculated that it was "TwentyFourSeven" by Artful Dodger, but it has not been fully confirmed.
The song that plays is Prologue by Jeremy Zuckerman. The song is edited to fit the beginning.
if you get Shazam on your phone you can watch episode 33 and let it do all the work for you.
Goo goo dolls - sympathy
If you're referring to the episode, "Privilege", then the song playing at the beginning was "Pride" by Syntax.
Nine Inch Nails - Capital G
"the WORLD" by Nightmare .
Somewhere Over The Rainbow
it is by the sugababes