Ok, so for "Magical Sound Shower" it's 40 songs in total, which means you have to keep track. Well here's a list of all the songs for ever track.

Note: You can get the trophy on the 1st 8 tracks in the game. Meaning you don't have to race on the other tracks you purchased for the trophy.

Here's the full list of songs for the trophy:

Seaside Hill Song List:
Track 1: Seaside Hill – Sonic Heroes
Track 2: Palmtree Panic (Present) – Sonic CD
Track 3: Can You Feel the Sunshine – Sonic R
Track 4: A New Day – Sonic Rush
Track 5: Windy and Ripply – Sonic Adventure

Casino Park Song List:
Track 1: Casino Park – Sonic Heroes
Track 2: Back 2 Back – Sonic Rush
Track 3: Bingo Highway – Sonic Heroes
Track 4: Super Sonic Racing – Sonic R
Track 5: Be Cool, Be Wild, Be Groovy – Sonic Adventure

Final Fortress Song List:
Track 1: Final Fortress – Sonic Heroes
Track 2: Metal Scratchin’ – Sonic Rush
Track 3: What U Need – Sonic Rush
Track 4: Final Egg: Crank the Heat Up!! – Sonic Adventure
Track 5: E.G.G.M.A.N. Instrumental – Sonic Adventure 2

Jumble Jungle Song List:
Track 1: Monkey Island
Track 2: Party Game 1
Track 3: Party Game 2
Track 4: Ultra Heaven – Super Monkey Ball: Banana Blitz
Track 5: Monkey Race

Tokyo-to Song List:
Track 1: The Concept Of Love – Jet Set Radio Future
Track 2: Sneakman (Toronto Mix) – Jet Set Radio Future
Track 3: Funky Dealer – Jet Set Radio Future
Track 4: Let Mom Sleep (No Sleep Remix) – Jet Set Radio Future
Track 5: Fly Like A Butterfly – Jet Set Radio Future

Carnivaland Song List:
Track 1: Samba de Janeiro – Samba de Amigo
Track 2: Carnival
Track 3: Bum Bum
Track 4: Vamos A Carnival – Samba de Amigo: Ver. 2000
Track 5: Mambo De Verano – Samba de Amigo: Ver. 2000

Blizzard Castle Song List:
Track 1: Tumbling Xylophone – Billy Hatcher and the Giant Egg
Track 2: Bossa Nova of Briny Air – Billy Hatcher and the Giant Egg
Track 3: A Jack-In-The-Box! – Billy Hatcher and the Giant Egg
Track 4: Volcanic Orchestra – Billy Hatcher and the Giant Egg
Track 5: Billy’s Courage – Billy Hatcher and the Giant Egg

Curien Mansion Song List:
Track 1: Hope With Doubt – The House of the Dead 4
Track 2: Into the Dark
Track 3: Aura of Dread – The House of the Dead
Track 4: Theme Of The Magician – The House of the Dead
Track 5: Restoration of Terror

Got this from Gamefaqs.com

Hoped I helped!