See the first post in this thread: http://www.head-fi.org/t/633006/aune-t1-usb-tube-dac-amp-discussion-thread-see-first-post-for-faq
Author has tested:
- Sansa Clip+, IPhone 4, Sony S639f, S: Flo 2, Ibasso D1, and HRT Headstreamer, Channel Islands Audio VHP-2, AMB Mini3, Digizoid ZO v1 (not really an amp but acts as one), and Audioquest Dragonfly
To your question, I will just use 1 = ipod with earbuds and 10 = the ultimate headphone experience, and just my opinion of course:
1) laptop + X1 = 3.5 (depends on laptop, bass is boomy and a bit wild)
2) E17 + X1 = 4.5 (sound is a little improved, overall sound seems compressed a bit)
3) Z + Starlight + X1 = 6 (bass is well controlled, vocals/strings really start to "sing")
4) T1 = will have to get back to you