I went through about a dozen small monitors in my office system. I would stay away from active studio monitors for what you are seeking here. They will likely not fit the #1 & #3 criteria in your OP. For what you seek here is my top 5:
1) 47 labs 4722 lens. Magical little speakers that have bass down to about 40Hz and are a little rolled off on top. Hard to find but you should listen if you can. Very small. Of all the speakers I've had you seem to be describing this one. I like them with my MC275 so a small tube amp would work. A gaincard or switching amp might be best though. I'd recommend 25wpc-50wpc.
2) Von Schweikert Unifield One. May be a bit over your budget but these speakers are awesome! The clarity and detail I heard with pro monitors without the fatigue. I listened on both tube and ss and they sounded nice on both.
3) Harbeth hl-p3es-2 sounded very sweet but for me they needed a sub. They also sounded best with a larger SS amp.
4) Merlin tsm-mxe. The are transparent and very dynamic but they seem to be quite sensitive to upstream components and recording quality, this may cause some issues in the highs for you. I found they work best if you have some space around them and you have some distance from them. Not their best in the near-field. Bass was plentiful, tight, controlled and not boomy at all. They too remind me of active studio monitors.
5) Green Mountain Rio. At 40+ lbs each these don't meet your weight limit but they are not too big. The cabinets are made of a stone-like material. These sound really good and dynamic at low volumes so they might be a good match for a bedroom system. They are dynamic and have excellent bass control. They might be a bit to "accurate" to give you that silkiness you seek.
hope that helps
1) 47 labs 4722 lens. Magical little speakers that have bass down to about 40Hz and are a little rolled off on top. Hard to find but you should listen if you can. Very small. Of all the speakers I've had you seem to be describing this one. I like them with my MC275 so a small tube amp would work. A gaincard or switching amp might be best though. I'd recommend 25wpc-50wpc.
2) Von Schweikert Unifield One. May be a bit over your budget but these speakers are awesome! The clarity and detail I heard with pro monitors without the fatigue. I listened on both tube and ss and they sounded nice on both.
3) Harbeth hl-p3es-2 sounded very sweet but for me they needed a sub. They also sounded best with a larger SS amp.
4) Merlin tsm-mxe. The are transparent and very dynamic but they seem to be quite sensitive to upstream components and recording quality, this may cause some issues in the highs for you. I found they work best if you have some space around them and you have some distance from them. Not their best in the near-field. Bass was plentiful, tight, controlled and not boomy at all. They too remind me of active studio monitors.
5) Green Mountain Rio. At 40+ lbs each these don't meet your weight limit but they are not too big. The cabinets are made of a stone-like material. These sound really good and dynamic at low volumes so they might be a good match for a bedroom system. They are dynamic and have excellent bass control. They might be a bit to "accurate" to give you that silkiness you seek.
hope that helps