Well I thought I would contribute instead of lurking and adding an opinion to some threads for one thousand posts.
So this thread is about Amp's and the synergy they have with certain headphones.
Just the few amp's I have herd I will list and I would appreciate it if people could contribute, and possibly answer a question of mine.
Little Dot 1+ stock tubes:
AKG k271, Great synergy, Provides a bump in the upper mids and Powers them perfectly.
AKG K601: Fairly good synergy, they get a bit of a sizzle form the tubey sound and are powered nicely, the downside is they ass an almost pipe sound stage rather than an open sound stage.
Ultrasone HFI-580: Okay Synergy, not the greatest synergy as it sucks some of the bass out and the 580's are not dark sounding headphones and gives them a super hot treble almost pain full. Powers them excellently but so does an Ipod.
AKG K500: Fantastic Synergy.Well these are the definition of bass less, I got over that and this amp Powers them great, it brings forth the already in your face mids without destroying the sound signature.
Sennheiser HD448: Not so great Synergy. These are dark and lushes sounding headphones; this amp loses the bass with this headphone and it will slightly eliminate the veiled mids but it makes them sound slightly aggressive.
Sennheiser HD25-II: 50/50 on synergy: these don't have the sennheiser sound so they are a bit more forward. This Powers them well but adds to much sizzle in the upper mids.
Little Dot MKII+ Stock rollers, 6n6Power tubes:
AKG K271: 50/50 Synergy: These are hard to power and the MKII+ just does not have the current to power them to their fullest. The amp is a relatively dark one and bumps the bass a bit adding a more smooth sound to these analytical cans.
AKG K601: Okay Synergy: I liked the sound of these from this amp, a little more relaxed tone with the darkness of the amp but it Powers them fairly well. the mids shine through and the highs are still full of life.
AKG K500: Pretty good Synergy: Well this amp Powers them well set to high impedance and it adds just a slight hint of bass to these absolutely BASS LESS headphones. the sound stage of this amp is a much much more open one than the 1+, the mids are relaxed a bit instead of it's almost harsh sound signature.
Ultrasone Hfi-580: KABOOM!!!!: Spot on synergy, Powers them super but these are efficient headphones so that's no biggie. The bass cannon nature of these headphones really shines through with this amp and the highs and mids are relaxed a bit of their sharp presentation.
Sennheiser HD448: Oh yesss: The synergy of this amp and this headphone is just wild. Bass shines though and adds a grainy color to the mids and makes female vocals just melt.
Sennheiser HD25-II: Pretty good Synergy: This Powers them well, gives them a little more bass than I would like to them. Mellows out the highs and leaves the mids relatively unaffected.
I will post My Idecco K702/601/HFI580 impressions later but now for a question. Does the Grado RS-2/1/i benifate from a darker tube amp?