With a quality 30 watt tube amp, I would also recommend Reference 3A. The DeCapos are a very good sounding speaker. I have the non-"i" version and find them to be a very nice sounding speaker. The non-"i" version tend to take just a little sparkle off of the top end in my system. This is not a bad thing as they tend to not exagerate the top end sizzle found on many mass market recordings. This leaves me with a very relaxed, natural sound, but also maintains plenty of detail.
The other great thing about the DeCapos is that they are very popular. You could buy a pair, try them in your system and re-sell them if you did not love them.
Enjoy,
TIC