I was using the SR-60 w/flats along with my mach speed tablet and thought it sounded pretty good overall and didn't leak enough sound to bother people on the plane. After 6 years, the cable tore so I needed something else for my last impromptu trip. I tried Sennheiser 558, 518, 598, PX 100, 201, 398, some Shure phones that I didn't like, AKG K99, ATH-M50, basically everything you see at Sam Ash, Guitar Center, and Audio Consultants(pretty much all the Grados, a few Stax, and most Senns). I also bought and returned an Audio Technica WS55. None of these places has headphone amps really. I noticed that the 558 sounded much better when I connected to Best Buy's display vs plugging them directly into the tablet. Same deal with the Sam Ash headphones when listening to them through Sam Ash's stuff instead of the tablet.
I could comment on all these phones when plugging them into the tablet, but I want to narrow the focus. What I will do is give background on what I tried since I don't post very often. When I do research on here and elsewhere, I always find that people will often have opposite opinions on the sound of the same piece of gear. I tried most everything in every room at CanJam 2010 aside from the JH Audio stuff. At that time I liked the RS-1 best. Out of everything there, I only had interest in the K701 and the Beyer stuff(770, 880, 990, T1). I liked the wide, airy sound of the RS-1. Nowadays I don't listen to it at all after getting a DT 990 600 ohms and then a K701(which replaced the 990 as my favorite). I liked the bass on the 990, but preferred the clarity of the 701. I like the 558 and the Px100, but I don't really care for any of the other Senns. I've tried the 650 and HD 800 on various setups at Can Jam and stores and still don't like them. I've also tried the AKG 550 at Best Buy and thought they were too bass light and didn't really have anything I liked in the 701. One thing I'll also note is the source material. I generally don't buy remasters and try to seek out the best pressing available of an album. I think it is important to note if someone is using a Jon Astley mastered cd or one mastered by Steve Hoffman. I find huge differences in 1980s cd pressings of the same album by bands like Europe, Judas Priest, and Sabbath. I listen to a wide variety of stuff. Not a lot of Jazz, Rap, R&B, or Country. Mainly various forms of rock, metal, film scores, dance, pop, and not many albums made in the last decade.
What really made the 701 my #1 was the soundstaging and the way it does vocals. I really like when overdubbed vocals get a huge sound that can expand a lot, deep and wide. That's the main draw of airy phones for me. I liked the horizontal expansion about the RS-1, but was always feeling like they were too glaring at times. The 701 gives the music a lot more breathing room and depth than an RS1. Anyway, I tried the AKG 240 and thought it had great sound for the most part. Does a lot of what I like about the 701, just with more bass and less clarity. Plugging them into the tablet does not give enough volume. I just learned that plugging my Ibasso P2 into the tablet is a no-no. It produced bass bloat but got me the volume I needed. Finally got back and plugged the 240 into my home setup of Arcam 73 and Heed Canamp. I found the Heed better for the 701 than the Darkvoice 332. The 240 fixes the often anemic bass of the 701, but falls apart when rock or metal music gets heavy. The bass ramps up too much and the sound becomes muddy. It reminds me of when I'd turn the bass boost on when listening to a discman.
The 701 seems very much like a pure analytical headphone. Everything is clear and can be heard. The 240 gives some toe-tapping, head-banging type sound with the extra bass that I just didn't get with the RS-1 or 701. It's soundstage is slightly less deep and wide when compared to the 701. I had brought my RS-1 to Can Jam and some stores. Plugged it into just about every source I could find at those places. I didn't like anything better than the Arcam 73 and Darkvoice I was using at the time. Koss Ksc35 is another one I like. It's not as good in the tablet as it was in my panasonic discman. A lot of times I felt like I enjoyed music more with those in a discman than the RS-1 at home despite the Ksc35 lacking a lot of the clarity and detail of the RS-1.
Now I'm debating what to look at next because after hearing the 240, it's a lot tougher for me to listen to the 701 for anything other than film scores. What I'd really like is a 701 with more bass that doesn't mess up the sound stage or the other parts of the sound spectrum. It gets the orchestra stuff correct, but that's kind of where it ends. Still comes off pretty analytical above all else. People had recommended me the K1000 years ago. I'd really like to try some of these other AKGs that are in production. K44 and K99 are too muddy, so I suppose I want to stick to bigger phones. Maybe get a portable DAP of good quality and one of the Fio amps. I've heard of the various mods and recabling, but never tried any of them aside from the ALO version at Can Jam. I forget what their source was. I think it was something plugged into an IPod. At the time, I liked the RS-1 better than what they had. I remember how laid back the Woo Audio tube amps made the 701 sound too. Interconnects make a big difference in my system. I forget why, but I plugged in some cheap interconnects not that long ago. Some albums were more harsh than I recalled. Then I plugged my Transparent Audio TL 100 interconnects back in and those albums were no longer harsh. I had tried various cables from Transparent at the time I bought those.
I guess this is what makes headphones a difficult hobby. I'm not sure that there is anything close to a perfect headphone. Then there's the issue of not being able to try the majority of this stuff before buying.