Guys, I'm really sorry for taking so long to reply!! For some reason I stopped receiving those e-mails that let me know when someone replies to the topic, so I thought it was forgotten hahaha!
First of all, Tulio, great to see you around here!!
Moonboy and goodvibes, to be brutally honest, I mostly used the JH13 with my iPod, since it's what I reckon most people would do with an IEM. I guess right now my best combo is the Marantz BD7004 as a transport, the ECD-1 and the PM-11S2. I tried them with the earphones and I found that while it improved the experience on almost all accounts, at some points it kind of overemphasized the bass a bit and it only addressed the treble issue slightly. The sound seemed to open up compared to the dark sounding iPod Classic, but the treble still sounded thinner than what I'd consider ideal. It's still not something that bothers me much since I'm still pretty much astonished at how good those IEMs can sound. With the Marantz and the ECD-1, the mids sound a lot more open and, while the bass goes a bit too far, the integration between the frequency ranges sounds more linear and natural. The treble also sounds somewhat more "attached" to the midrange, if that makes sense.
I used to have a Little Dot MKIII, but unfortunately I sold it to fund an O2 and an eXStatA, but I'm planning on getting a Little Dot MKVI+ as well to power the K1000. So the best amplifier I can give the JH13s now is the Marantz!
Also, goodvibes, thank you a lot both for the compliment and also for the additional information!! I didn't know that Laserdiscs were good transports. I'm actually not using mine right now since it's only working when it feels like it... I'm also curious about the PM-11S2. I really don't know where the headphone out comes from, but it didn't have the guts to drive my previous K701 that well!