- a NOS (new old stock) RCA 6BQ7A from US/1983,
- a USED Amperex 6DJ8 from Holland/1965,
- a NOS Voskhod 6H23N from Russia (military)/1972,
- a NOS Sylvania 6DJ8 from US/1980,
- a NOS Tesla ECC88 from Czech Republic/1970.
To go more expensive and rare will require >$40 each and some folks spend thousands - dunno if I'll go there. I choose test tracks not for specific fidelity or range but for stuff I like. It's probably a dumb test for fidelity as I first look for clever songwriting - except The Killers who have style not songwriting. I do add a Flim & The BBs track for range and dynamics specific listening (heck it's got a 22Hz note in there). Test 368Kbps tracks include some of my favorites like:
- Wheatus/The London Sun/Too Soon Monsoon/2005
- Wheatus/The Truth I Tell Myself/Too Soon Monsoon/2005
- Wheatus/Punk Ass Bitch/ Wheatus/2001
- The Killers/Miss Atomic Bomb/Battleborn/2012
- The Killers/Spaceman/Day & Age/2008
- The Killers/For Reasons Unknown/Sam's Town/2006
- The Killers/Smile Like You Mean It/Hot Fuss/2004
- Big Star/The Battle of El Goodo/Record #1/1978
- New Pornographers/The Laws Have Changed/Electric Verison/2003
- New Pornographers/Crash Years/Together/2010
- New Pornographers/Letter From An Occupant/Mass Romantic/2003
- Essex Green/This Isn't Farmlife/Cannibal Sea/2006
- Vampire Weekend/Oxford Comma/Vampire Weekend/2008
- Vampire Weekend/Holiday/Contra/2010
- Vampire Weekend/Diane Young/Modern Vampires of the City/2013
- Flim & The BBs/Funhouse/Big Notes/1985
So listening to 90 minutes of stuff over and over requires listening without fatigue - which was a primary measure I used in comparing. At the end of the day, hearing the differences is hard. All subjective notions include:
- Listening Fatigue (gotta be able to keep the headset on)
- Low Noise (noise floor - don't want hiss or hum on quiet parts)
- Dynamics (speed of recovery to play the next note/passage)
- Power Over Range (highs and lows strong)
- Smooth v Harsh (self explanatory but it's a feeling)
- Midrange-Forward (if any, prefer forward voices and clarity there)
It was a good test and very hard to discern differences in many cases... my preference at this point is: