Which very dynamic speakers would you recommend?

Keep Canada green, buy a pair of Paradigm Studio 100 v2s.

Affordable. Good beyond their price and big enough to give you extended low frequency response and efficient enough to provide excellent dynamics. To alleviate any fear of the tweeters, may I recommend a simple tweak I made to mine: get some self-adhesive felt (black is the best since it does not call attention to itself) carefully cut it with an X-Acto knife to match the outside diameter of the tweeter and apply it.

I can't say I heard any marked improvements, but it can't hoit.

The number of speakers available is considerable. The one thing you owe to yourself is to evaluate each pair in conditions as near to the actual listening conditions existing in your home as possible. Your own room is the ideal. Use only recorded material you know very well and don't let the retailer go through his usual demo shtick to steer you to what he has in stock or provides him with the best markup. Avoid the flavour of the week syndrome. Buy a product from an established manufacturer.

I will not get into a discussion over the meaning of "dynamic" as this could lead to endless debate. I use it in the true meaning of the term: an ability to follow the changes in volume of the music at realistic volume levels at the range of frequencies that count. To fellow 'Agon devotees, don't bother me with such things a "microdynamics", "mid-range bloom", "back to front depth" "width of image" "inner detail" (as opposed to "outer detail" I guess) etc. or how many angels can dance on the head of a pin: this person said "dynamic", remember. Buy dynamic speakers (no joke, I mean the ones with cone/dome drivers, magnets, a dreaded x-over and a box to clothes the whole shebang), the other types will cause you more grief than they are worth. Oh, and if you want something that looks like a smoked ham, give Norh a smell, eugh, listen.

I second Pbb's motion enthusiastically. Paradigm is a brand that some audiophiles love to hate because (1) they sell a lot of speakers and (2) they are a Big Corporation.

The reference series offers incredible value for money. The TOL Studio 100 has gone head to head many times with speakers selling for 2-5 times as much and has held its own admirably. I use them for HT but, you know, if I had to sell my 2-channel speakers life as I know it would not end.

Just a couple of things to keep in mind. First, they love power. Second, they aren't the best choice of quiet background music. They like to sing!

Pbb is dead on -- try it in your own environment if at all possible. I like the 100 v2 as well. If you like something with more presence, try one of the Thiels (the 2.3 is very nice). If you like something super smooth throughout, check out the Montana line-up. Good luck.
By the way, if you can't find the self-adhesive felt, you can buy tweeter surrounds for $10 or so here on Audiogon -- look for the billboard.

The Paradigms are an excellent choice. For the types of music you like you might want to give the less expensive Alons an audition as well; very open sounding and dynamic.