My experience has been different from yours. For me the biggest difference has been from 1 to 2 ohms, and yes 2 and 10 ohms sound very similar but slightly different as well. All of the cans I've tried couldn't be more different....jh13pro, w3000anv, he-6. With my jh13pro the imaging is better focused with the 1 ohm output. The sound is actually a touch louder once I move it to 2ohm. The sound stage also gets a little smeared. The effect is just slightly greater at 10ohms. I like the 2 ohm output best with my w3000. The sound stage is a little smaller with the 1 ohm ouput.
With my jh13pro being 28 ohms they're not as prone to hiss as most ciems. So even with the gain switch in the second position, the background is still dead quiet. And I prefer them at that gain setting as well. They sound a little too polite, and a little too smooth in the lowest gain setting. With the gain in the second postition, the sound is a bit more lively and balanced as well. I recently got a new 6n silver cable for my jh13 to go with my m8. It's terminated single ended, but I wanted it that way to directly compare it with a stock ue cable that I've been using for a while now. It was my intention on reterminating balanced. But it sounds so good as is, I don't know if it would be worth the trouble to go balanced. What I hear is very reminissent of my audition with them on a gsx mkII. No I'm not saying the m8 is just as good. But the jh13 do sound very similar to what they sounded like on it though. Maybe it's the class A thing, I don't know. But that's still high praise to even mention them both in the same sentence. The great thing about this product is, it can be tailored to everyone's taste, and tailored for different cans at the same time. So everyone's results may be different.
Edited by moodyrn - 7/19/13 at 12:01pm