the big one: how do you choose speakers? By what features, data?

@kokakolia looks cool but no OGY distributors in the US

"I have a 100Watt into 8Ohms amp but my room is small, so that won't matter much."

@grislybutter yes it will very much so. speaker sensitivity and amp power and current capabilities are critical or matching these two components and their working properly, regardless of room shape and size. the speakers and amp are working together no matter what room theyre in. 

Unless one is considering extraordinarily difficult to drive speakers and a requirement to play at extremely loud levels, I would expect 100 watts to be plenty, and, power is not a concern.  However, amps are critical to the sound of ANY speaker and quality of whatever watts it delivers matters a lot. 

I personally like low-powered tube amps the most, assuming they are used with compatible speakers, because they tend to be lively, engaging (keeps my attention), and at the same time do not sound edgy or hard and brittle.  Most high end, high-powered solid state amps are not offensive ((not "grainy" or "harsh" as some tube lovers claim, but, to me, they sound a bit lifeless and unengaging at lower volume levels.  I tend to not like most very high-powered tube amps because they have a hardness or "glare" I find a bit annoying in long-term listening sessions.

that is not to say I don't want (to try) another amp but it's definitely not my bottleneck. My current speakers are very musical, but a bit muddy and have too much bass at the expense of the midrange. Which is probably by design, for this price range and components, it's giving the listener a lot of bang - literally

IMO many audio buyers allocate an excessive amount of money towards loudspeakers neglecting electronics/source/cables and room treatment. The outdated theory of spending 50%(total system cost) on speakers was created by the industry to keep one upgrading(unhappy) electronics and source components.