But in retrospect and the residual discoveries since, this was an incredibly deep year. A lot of technical death metal and progressive college rock. A lot of EPs stood out as well as I think I have 9 in the list below me.
Comparing to 2005 may be unfair, and other years of the 2000's, but I'd say it measures up in a lot of ways, although possibly the depth is more a product of music in the 2000's, the amount of good new music that was coming out.
Blackfield and The Velvet Teen are not far behind..nor is Orphaned Land and some others. I'd say 2004 has become more of a revered year for music for me after now revisiting this.
1. Marillion - Marbles
2. Blackfield - Blackfield
3. The Velvet Teen - Elysium
4. Orphaned Land - Mabool: The Story of the Three Sons of Seven
5. Fates Warning - FWX
6. Brian Wilson - Smile
7. Oceansize - Music for Nurses [EP]
8. 3 - Wakepig
9. The Dissociatives - The Dissociatives
10. Umphrey's McGee - Anchor Drops
11. Clann Zú - Black Coats and Bandages
12. Pain of Salvation - 12:5
13. Fair to Midland - inter.funda.stifle
14. The Decemberists - The Tain [EP]
15. Disillusion - Back to Times of Splendor
16. Crotchduster - Big Fat Box of Shit
17. Pain of Salvation - Be
18. The Dear Hunter - Dear Ms. Leading
19. Archive - Noise
20. Subterranean Masquerade - Temporary Psychotic State [EP]
21. Akphaezya - Anthology II: Links From the Dead Trinity
22. Meshuggah - I [EP]
23. Thurisaz - Scent of a Dream
24. Behemoth - Demigod
25. Superior - Ultra Live
26. The Apex Theory - Inthatskyissomethingwatching [EP]
27. Mastodon - Leviathan
28. Brazil - A Hostage and the Meaning of Life
29. Enchant - Live at Last
30 .Martin O'Donnell and Michael Salvatori - Halo 2 Original Soundtrack
31. Cloud Cult - Aurora Borealis
32. Aereogramme - Seclusion
33. King's X - Live All Over the Place
34. sElf - Ornament and Crime
35. Best Friends Forever - Best Friends Forever
36. Porcupine Tree - Warszawa
37. Judgement Day - Dark Opus
38. Hope of the States - The Lost Riots
39. The Polyphonic Spree - Together We're Heavy
40. Malajube - Le compte complet
41. Biffy Clyro - Infinity Land
42. Bloc Party - Bloc Party [EP]
43. Deerhoof - Milk Man
44. Time of Orchids - Early as Seen in Pace [EP]
45. Anathallo - Hymns [EP]
46. Janus - Armor

Archer Avenue - I was an Astronaut
rel January 2004

Time of Orchids - Early as Seen in Pace [EP]
rel January 1, 2004

Circles Takes the Square - As the Roots Undo
rel January 6, 2004

John Vanderslice - Cellar Door
rel January 20, 2004

Blackfield - Blackfield
rel January 2004

Porcupine Tree - Warszawa
rel January 2004

Pain of Salvation - 12:5
rel February 23, 2004

Orphaned Land - Mabool: The Story of the Three Sons of Seven
rel February 23, 2004

Falling Up - Crashings
rel February 24, 2004

VAST - Nude
rel February 24, 2004

The Decemberists - The Tain [EP]
rel March 4, 2004

Decapitated - The Negation
rel March 9, 2004

Deerhoof - Milk Man
rel March 9, 2004

Archive - Noise
rel March 23, 2004

Subterranean Masquerade - Temporary Psychotic State [EP]
rel March 23, 2004

Arsis - A Celebration of Guilt
rel March 30, 2004

The Dissociatives - The Dissociatives
rel April 5, 2004

Proto-Kaw - Before Became After
rel April 5, 2004

Disillusion - Back to Times of Splendor
rel April 6, 2004

of Montreal - Satanic Panic in the Attic
rel April 6, 2004

Evergrey - The Inner Circle
rel April 27, 2004

Marillion - Marbles
rel April 27, 2004
Thurisaz - Scent of a Dream
rel May 3, 2004

Feist - Let it Die
rel May 17, 2004

Secret Machines - Now Here is Nowhere
rel May 18, 2004

Bloc Party - Bloc Party [EP]
rel May 24, 2004

Ayreon - The Human Equation
rel May 25, 2004

sElf - Ornament and Crime
rel May 2004

Clann Zú - Black Coats and Bandages
rel June 1, 2004

Fair to Midland - inter.funda.stifle
rel June 5, 2004

Midlake - Bamnan and Silverlake
rel June 8, 2004

Cloud Cult - Aurora Borealis
rel June 22, 2004

The Polyphonic Spree - Together We're Heavy
rel June 30, 2004

Umphrey's McGee - Anchor Drops
rel June 29, 2004

Meshuggah - I
rel July 13, 2004

Strata - Strata
rel July 27, 2004

Necrophagist - Epitaph
rel August 3, 2004

The Velvet Teen - Elysium
rel August 3, 2004

Laura Veirs - Carbon Glacier
rel August 24, 2004

Mastodon - Leviathan
rel August 31, 2004

The Felix Culpa - Commitment
rel September 1, 2004

Augury - Concealed
rel September 4, 2004

Kasabian - Kasabian
rel September 6, 2004

This Day and Age - Always Leave the Ground
rel September 7, 2004

Tears for Fears - Everybody Loves a Happy Ending
rel September 14, 2004

Aereogramme - Seclusion
rel September 23, 2004

White Willow - Storm Season
rel September 21, 2004

Sonata Arctica - Reckoning Night
rel September 22, 2004

Brazil - A Hostage and the Meaning of Life
rel September 26, 2004

Pain of Salvation - Be
rel September 27, 2004

Brian Wilson - Smile
rel September 28, 2004

Mutemath - Reset [EP]
rel September 28, 2004

Best Friends Forever - Best Friends Forever [EP]
rel September 2004

Biffy Clyro - Infinity Land
rel October 4, 2004

Crotchduster - Big Fat Box of Shit
rel October 5, 2004

Dream Theater - Live at Budokan
rel October 5, 2004

Fates Warning - FWX
rel October 5, 2004

Behemoth - Demigod
rel October 11, 2004

Oceansize - Music for Nurses {EP]
rel October 11, 2004

Superior - Ultra Live
rel October 23, 2004

Happy the Man - The Muse Awakens
rel October 25, 2004

Jon Oliva's Pain - 'Tage Mahal
rel October 25, 2004

Sleepytime Gorilla Museum - Of Natural History
rel October 25, 2004

3 - Wakepig
rel October 26, 2004

Enchant - Live at Last
rel October 26, 2004

Courtney Yasmineh - Sufi Line
rel October 26, 2004

King's X - Live All Over the Place
rel November 2, 2004

Malajube - Le compte complet
rel November 2, 2004

Quo Vadis - Defiant Imagination
rel November 4, 2004

Wastefall - Soulrain 21
rel November 7, 2004

Martin O'Donnell and Michael Salvatori - Halo 2 Original Soundtrack
rel November 9, 2004

Judgement Day - Dark Opus
rel November 23, 2004

Akphaezya - Anthology II: Links From the Dead Trinity
rel 2004

Anathallo - Hymns [EP]
rel 2004

The Apex Theory - Inthatskyissomethingwatching [EP]
rel 2004

Cavil at Rest - Cavil at Rest [EP]
rel 2004

The Dear Hunter - Dear Ms. Leading
rel 2004

Janus - Armor
rel 2004