You may want to reconsider purchasing an amp. It seems to be to be a better selection to pursue speakers you adore. Hear them in a setting with fantastic pre/amp, or even better yet, an fine quality tube hybrid integrated amp.
Why? Because you may change your mind later about which amp you want. If you purchase the amp now, and later select speakers, you may not like what you hear. you may find yourself purchasing yet another pre/amp because it does not mate well enough with your speakers.
If you get fine speakers now, any future upgrade will continue to allow the speakers to impress you, especially if you chose them by listening to fine equipment!
I would think the speakers will bring a much more dramatic improvement short term, and make it easier to shop ONCE for the pre/amp (OR! Tube hybrid integrated) later.
Word of caution, I would NOT use your current equipment to judge the speakers in question! Hear the desired speakers in the best setting possible. You will enjoy working toward that sound later as you upgrade amp.
If you are relatively new to hifi, you may be looking for inexpensive solutions to "upgrade fever." Try to avoid that. I thought exeactly the same as you; "...maybe if I can get an amp for a couple hundred, I can kick up the performance..." In reality, the addition of another piece of electronics, tethered by an additional pair of interconnects, etc. will kill much of the finesse and detail you could achieve by moving to such as an tube integrated!
You would likely see a bump in power/presence, but that may not satisfy long term.
I have moved to the absolutely most simple system possible, and with terrific results. I would avoid any unnecessary components if you are looking for purist sound. Better to save up and get the right piece for the job.
Now, you MAY wish to pursue the tube hybrid integrated, or simply a better quality solid state integrated (imho, you will leapfrog a few upgrade steps if you go right for the tube hybrid and they are NOT all that unresonably priced! Especially here on agon!; Just make sure you get one w. a remote if you gotta have it!) and then look for speakers later. That decision may be determined by how good your main speakers are now. If they are nothing special, then definitely do the speaker thing first! If they're pretty good, and you love them, then go for the amplification.
You'll hear everything under the sun about which to start with in building a great system...cdp...amp...speakers, etc. In the end, system symmetry/complimentary (i.e. same level of quality) of components seems to have a huge impact on overall enjoyment. If you get serious about this hobby, you'll want to someday own two cdp's or sets of speakers (at least temporarily) to really find the magic in the sound.
The truth is, if you are getting serious about pursuing great sound (you have to be honest and determine if you're a "tweaker" or not), you'll most likely change amplification and speakers several times before it's over.