Bookshelf Speakers - Musical Fidelity A300 & Rock

Nothing Rocks like an ATC SCM-12, if you have a smaller sized room these speakers work well against the wall. In a larger room you can sink the full power of the A300 into these speakers with no worries.

2nd pick would be whatever Dynaudio fits your budget with a 6" woofer, 3rd pick would be at a little higher price range is the Dali Helicon 300, especially with your preference for a vinyl source these speakers could sneak past my previous recs in your system.

Polk, Paradigm, B&W are very good but are not on the level of these lesser known speakers who use much better drivers (woofers/tweeters) and who have as good or better skill in their execution of design.

Good recomendations.
The NHT SB3 would be a great budget bookshelf. It is a little bright and extends pretty darn low for a bookshelf. If you need extended highs and are on a budget or can afford to experiment with less expensive speakers the SB3's are wonderful.

Slate1

I own a pair of LSi15s and at first I thought the tweeter was kind of laid back too. Then I removed the grills, gave them so toe-in, and replaced the flat jumpers with some quality ones(Maybe you already tried all this), and bingo, it was perfect. I would also recommend giving them some time to break in. The thing about that tweeter(IMHO) is that is so damn accurate, and uncolored, it kind of takes time to get used to it too. It doesn't call any attention to itself, but at the same time, it gives me all the detail there is to give in a totally unforced manner. Once I figured this out, others speakers seemed bright (maybe even a little hard) by comparison.

Again removing the grills, and replacing the jumpers gave the LSi15s the little bit of sparkle I thought was missing, without making it bright or anything like that.

If that still doesn't work for you, maybe some of the recommendations that were given may be better choices. I would also recommend you check the Amphion Argon2...

Just for reference, if it helps I'm using Analysis Plus Silver Oval cables(which I bought used here on Audiogon for a good price) and Analysis Plus jumpers. I'm also using a Perreaux Radiance R200i integrated amp(Awesome amp by the way) and a Sim Audio Nova LE CD Player. As for the kinds of music I hear(just for reference)...I listen to a lot of different kinds of music Pop, Rock, Jazz(specially like CDs where trumpet is the showcased instrument so to speak), Vocal Jazz, Latin Pop, Latin Jazz, Spanish Rock, R&B, and even some Hip-Hop...I sometimes use the song Ants Marching from Dave Mathews band's "Under the Table and Dreaming" CD to kind of get a handle on how my system is sounding.

Hope this helps...