New or used???

Rather than putting $5,000 toward speakers, you may want to consider putting something like $2,500 toward a good integrated tube amp (example: used VTL integrated IT-85) and the other $2,500 toward a used pair of Sonus Faber Grand Pianos or something similar. I fear your Bose 550 receiver may not be up to making music of $5,000 speakers and for that budget there are a lot of combinations folks could recommend. IHMO of course. Jeff

Jhkear,
Your initial post suggested, to me at least, that a speaker purchase was just your starting off point and that appropriate supporting equipment would be forthcoming. If your entire budget hovers around $5000 then Jj2468 is absolutely correct. Don't blow your entire budget on speakers. Use the audiogon classifieds and keep asking for help on these forums - there are some knowledgeable people here. IMO, the synergy between your equipment is more important than the equipment.

Regards

Tvad, this post screams for your input.

Jhkear,
If budget for everything is $5k (though your post explicitly states speakers only to start with), by all means spread it around. If just speakers, you will get a lot more bang for buck out of used than new.

I have bought almost everything used - speakers (twice), amps (3x), CD player (2x), preamp (1x), turntables (4x), phono (1x), crossover (1x), cables (several). The only stereo equipment I've bought new in the last 25yrs are a few odd accessories, a cartridge, a tonearm, and a phono stage. That and LOTS AND LOTS OF MUSIC.

If you want to spend your hard-earned money and keep what you buy for a long time, spend some time listening before you buy. Do a search of audio clubs in your area and see if you can't get invited to some members' homes for a listen. There are very few things which show up only once (so you can afford to wait), and there are certainly lots of choices in that price range if going used. For that money, definitely listen first. One could get large Thiels, nice Magnepans, Merlins, older Soundlabs, the Shahinian Obelisks (cheaper than $5k but I'd love to listen to them), you might find some used horns in that range, some electrostats such as Innersound or MartinLogan, and the list goes on... [disclaimer: no affiliation with anyone selling anything]

I apologize for seeming to mislead everyone. My budget for a system is around $10K, and the Bose definitely won't be a part of the system. I was thinking either separate amp and preamp or going with an integrated (I've heard both the Macintosh MA6900 and the Musical Fidelity A1008, and both were great), but any input is much appreciated. I did also hear the Grand Pianos and, although they were impressive, the Cremonas were clearly a big step up.

Nice sounding gear from the UK that has great synergy is the Rega Apollo CD player, Rega P3-24 turntable, integrated amps by either RFD or Roksan (I have the Kandy), and ATC 11 or 19 speakers or B & W 803s. NAD makes great amps, the 372 and M3, both made in China, which can be interchanged for the RFD or Roksan. The whole system will set you back a few thousand.