I just got a 550 and it does lack in bass to some degree. I mainly use it with a sansa clip zip and Ibasso P2 or Fiio E6. The Ibasso is definitely the better of the amps. I had also tried a sennheiser hd25-1 at guitar center with various types of music using the sansa and ibasso. I think I enjoyed that one a lot more than the 550, SR60 w/flats, RS-1, Samson 850, when it came to rock and metal music. It was exciting without being fatiguing, bass was more impactful than the 550, and I felt more into it than when I use my RS-1 in this setup. The AKG 240 would be great if not for the muddied lower frequencies. Everytime music would get into a section with a lot of bass, it felt like stuff just blurred together. That was using a tablet and the ibasso or arcam 73 and heed can amp. I might have better results using it with my sansa. They were going for $60 and free shipping on amazon a couple months ago. Last time I looked it seemed like they were back to $80. One of these days I'd probably get another one. I do plan on buying an hd25-1 soon, but I want to see if I can try an amperior first. SR60 with flats is really good. It gets a pretty wide sound and no bloated bass or fatiguing treble. It's just not as refined as an RS-1. The only thing I didn't like about the hd25 was that it seemed to sound too muddy with stuff like Death-Human or Morbid Angel Domination 1st press albums. Those albums do have a sort of muddy production, so it may not be the fault of the headphone. Film scores like Star Wars were pretty good on the hd25. Didn't sound as congested as with the Grado stuff. The 550 is awesome with film scores. The hd558 was also something I liked a bit, I just need to try it with a sansa and amp. I keep finding that most headphones have some sorta significant flaw and that it can be difficult to really find the right amps, cables, and sources since the only way to hear most stuff is to order it. I also plan to order an O2 amp. I ordered my 550 refurbed from crutchfield and since a $25 off $250 coupon sprung up when I was browsing their site, I basically got a 3.5 to 3.5 audioquest evergreen cable for free. That was an upgrade over the RCA 3.5 I was using, as the RCA was an upgrade over the $2 3.5 cable I got from fry's. I think the EQ on the Sansa helps the 550 a bit as I need to tweak it for a lot of stuff. Source recordings were a big thing too. With classic rock there's a lot of 1st press cds available. Sometimes the quality of the mastering varies a lot. Like with the Bowie RCA cds, various 1st presses of Black Sabbath. I know this is an issue with classic rock stuff too. The Steve Hoffman forums have good info. There have been times where just swapping one pressing for another makes a way bigger difference than switching any audio gear. I'm always surprised at reviews I read here and elsewhere that are almost exclusively using badly mixed and mastered modern music. That's not to say that older stuff is meticulous in its sound quality, just that newer stuff is usually more horrendous. I've heard some old cds like the John Lennon stuff have bad noise reduction. It's always frustrating when I havta leave an album on a lower volume than what I want because turning it up just ruins the whole thing. That applies to some classic rock remasters too.
I can't really say I'd recommend the Grados or anything else as amazing. I went to Can Jam before and at the time, I liked the RS-1 better than everything else. I heard the HD800 on multiple setups there and elsewhere and never thought much of it. Primarily I had been using the K701 with the arcam and heed, but now I kinda find it lacking in everything but soundstage. It's been sitting around since I got the sansa clip. I went back to the 701/Arcam setup yesterday and actually thought some stuff sounded worse than the sansa/550 combo. Hopefully I can do a good comparison with my current stuff and the 558, hd25, and amperior soon. Going off my memory, I'd probably take the HD25 over the others now. Too bad my sansa froze, I'm waiting on a replacement. They're so cheap that I may buy a backup player today. 550 definitely needs an amp and the right EQ, although they don't sound bad directly out of a Sansa. They do not sound good direct into my stock computer audio or heed and arcam. They also don't sound so hot out of the best buy magnolia display
