the smoothest sounding speaker

i would say a quad 57 is very smooth while still sounding like music. Likewise a spendor 3/5.

Aeriel 7Bs and Silverline Sonata IIs. I have owned them both, and didn't care for either of them. The Sonatas had a midrange coloration and the Aeriels sounded tight and closed in. Both average, but not exceptional speakers.

Oz

I personally love the Aerial 6's - I have a small square room (12 X 15)... lots of clean SS power (Levinson 23.5) and some acoustic room treatments. I am upgrading to the Aerial 9's as soon as I can find a nice set in Rosewood. I like the idea of the 20T ... but man, I just cant swing that much cash. For the price I thought the 6's actually sounded sweeter (less fatiguing) and had better imaging than the 7b's. I thought the 6's were a little weak when you hit higher volume levels - the 7b's did a much better job in that regard. The 9's were a combination of all the good in both the 6's and the 7b's...

Verity Audio Fidelio

I would suggest you check out Daedalus Audio. One of Lou's key design objectives is NO listener fatigue. I had the DA-1's for a couple years and they were the most non-fatiguing (yet lively and dynamic) speaker I've ever owned or heard--and I've owned several of the speakers mention such as Harbeth Compact 7's, Spendor SP1's and Spendor S100's. I've also heard the Aerial 7B's. If non-fatiguing sound is your thing, the Daedalus stuff is worth checking into. BTW, Lou is going to release several new models at the RMAF in a few weeks. He has two new "Reference Line" speakers and will be rolling out updated versions of the excellent DA-1 and DA-2. One of these models will be gracing my living room shortly. If your planning on being in Denver, go have a look.