an yeah grados (and magnums) truly shine on tubes...
I don't think that this can be emphasized enough. I used to really love listening to the Grado and Alessandro headphones on vintage receivers (Sansui, etc.). While I thought the vintage receivers did a much better job than some of the typical solid state headphone amplifiers, the tube amplifiers seem to have a much better pairing with the Grados. One doesn't need to spend big bucks on an amp either. The Little Dot I+ and a pair of trusty upgraded tubes (about $40) + $110 or so for the LD I+ for a total of about $150 and one is set. Of course, the DAC would need to be added into the mix.
My experience with using devices such as iPods, sound cards, etc. for input into an amp, or using directly to power the Grados isn't really too impressive. The iPod or even the Sansa Fuze will start to really exhibit their limitations. Personally, I feel they are better served with IEMs or ear buds in a portable situation. Also, sound cards really leave you in the hands of what the manufacturer wanted to push out as far as options go. I have the Asus Xonar DX and think the sound is OK. But, not nearly as good as going through a better DAC (e.g. HeadAmp upsampling DAC) and the Little Dot I+ is quite good. I wouldn't spend $500 more towards the DAC and amplification as one would only get a few % more out of performance, yet be $500 poorer.
Why do people like Grados so much?
Why? For me, I think it has a lot to do with my music preferences. Jazz, blues, female singers, etc. seem to really pair well with the Grado headphones. Female vocals are not sibilant like I've experienced issues with at times with other brands. Also, the Grado headphone (with the exception of the SR-325i / SR-325is) are some pretty light, and comfortable headphones. Some will comment and say the comfort isn't good or the headphones are not comfortable. I've found if the headband is too firm and pushing hard on my ears, I don't like the feeling either. But, when you slowly adjust the headband pressure so it is minimal with the grip and tightness, your comfort level will improve 100%. I've had issues with the L-Cush pads, the TTVJ Flats, etc. in the past and felt their were comfort issues. But, those issues were resolved with slightly opening the headband for less pressure on my ears.
Being able to pinpoint the instruments with accuracy - percussion, piano, upright bass, etc. is critical for my listening and that's how the Grado captures me and pulls me into the music.