The Shadow footprint is sure nice but over time I found it a bit too forward sounding and a little too much bass emphasis for my taste. Plus wasn't crazy about the volume control.
The Pure II is more laid back and relaxed with very wide stereo separation. I'm hoping the Picollo more matches the Tera's presentation.
I remember liking the Pico Slim with it in previous ownership but the turn on thump is off putting. The Meier Quickstep was very nice but a bit too big overall.
I fully agree on the volume control, after powering on I adjust it once to just before hiss kicks in and then only use the Tera's control.
I haven't heard the Pure II with the 846 because i didn't own them at that time. Your comparison sounds tempting actually but my current aim is to find my optimum sound without an external amp. Simply just don't want the hassle.
Have never heard the other amps you mention and (bit of topic) just ordered a Hifiman HM-802... :-)
Edited by ThaPapper - 1/13/15 at 3:35pm