Amplifier recommendations for LSA-1 Signature


I used to be a purely HT guy - had definitive technology 7006 speakers and Onkyo mid-level receiver driving a 5.1 setup. One thing I did not like about DefTechs was how the music sounded, I just couldn't stand to listen for more than 15 minutes. Then I read about listener fatigue and the so-called 'musical' speakers, and started looking for a new set of speakers that were more musical than the deftechs. This led me to LSA-1 Signatures. Now, I don't consider myself an audiophile even by a long shot but I can tell you that these speakers are something special. I can listen to jazz, classical and semi-jazz like norah jones or melody gardot for hours at a stretch and never get tired of listening. For some reason the same speakers sound pretty mediocre when listening to rock or even soft rock.
However, I listened to another setup at a friend's house (he was using B&Ws paired with B&K) and the same music was suddenly even better than in my setup. I won't pretend to claim that I understand what people mean when they use terms like imaging or dynamic or transparent, but it sure sounded wonderful!
Now, I cannot afford B&Ws - at least the nice ones. I auditioned the ones they sell at Best Buy Magnolia but just didn't like them much. So I'm thinking I can probably stay with LSA's and use a separate amplifier in conjunction with my Onkyo (110 wpc).
So my first question: Is it even worth adding a new amplifier? I am not necessarily after more power as I listen at low to moderate volumes, but that magical sound that I heard at my friend's house - clean, tight base and even better separation than what I can get with my current setup - but at the same volume.
Secondly, I cannot afford to buy expensive gear at this time. So I'm looking for used equipment around $1200. I generally like the laid back, smooth sound of the LSAs but sometimes I do wish that they had a bit more sizzle and oomph but not too much like the Paradigms (sorry don't mean to start a flame here but that's how I felt when I listened to the Paradigm bookshelf - Studio 20).
Any recommendations?

Current setup:
Onkyo HT-RC180 (110 wpc)
LSA-1 Signature (Front LR)
Definitive Technology (Center; soon to be replaced by LSA center)
Definitive Technology SuperCube 1 (sub)
Definitive Technology (surrounds)

Short term goal:
Add a new amplifier to improve 'musicality' - even if its at the expense of HT sound

Long term goals:
Replace Onkyo with a better PrePro
Replace sub with REL
128x128arafiq
If you are streaming CD quality music, the Apple TV should have no jitter over toslink. There is a really thorough analysis of the Airport Express on computeraudiophile.com that concludes this, and I'm assuming it would be the same for the ATV. Note: that is an assumption. :-)

If you go higher quality files than CD, or are using the built in DAC, then jitter is terrible. I was using an Airport Express to transport the digital music to the HK prior to the ATV, and haven't heard any difference personally.

Check out the review on CA and see if that helps. In my setup the weak link was the Marantz SR7001 I was using. I was streaming into the receiver DAC, and using the DacMagic for the Mac Mini only. Replacing it with a far superior amp and its DAC made all the difference. If you use the DAC in the Oppo, I'm sure it will be wonderful. If you are going to stream digital to a built in DAC, I'm not sure that jitter will be a big issue. But I'm not an expert.

Let the fun begin! :-D
Mot
Here is the link to that analysis.

http://www.computeraudiophile.com/content/466-measurements-first-and-second-generation-apple-airport-express/

Mot
After thinking this through I feel my situation is more similar to manoterror. I am also streaming music from my ATV to a mid-level AVR. Since almost all my music is CD quality (apple lossless), hopefully jitter won't be an issue if I keep ATV in the picture, at least this year.

I read a few HK990 reviews by both experts and users, and most of them are very positive. Unfortunately, I can't find a place in Dallas where I can listen to it. The prices on the internet vary between 1200 ('used', via Amazon) to 2399. Nothing used available at audiogon or local craigslist either.

Another integrated that is being compared to the 990 is Anthem 225. I have heard good things about Anthem but don't know how it really compares to HK990 SQ-wise.