If you are definitely planning on upgrading your speakers in the near future, I recommend that you not upgrade your preamp and amp now. (I realize that this is not what you want to hear, but IMHO, that is the best way for you to approach upgrading your system.)
Pick out the speakers that you want, and then match your future power amp, (or integrated amp), to your speakers.
The amp to speaker synergy is very important, and to pick your amp first, will limit your selection of speakers that will sound good with your amps.
(i.e. as examples; a power hungry speaker will not work with a low powered amp, or a speaker that has a very low impedance, may severely tax the power of an amp that does not double in power as the impedance is halved.)
My two cents worth anyway.
Pick out the speakers that you want, and then match your future power amp, (or integrated amp), to your speakers.
The amp to speaker synergy is very important, and to pick your amp first, will limit your selection of speakers that will sound good with your amps.
(i.e. as examples; a power hungry speaker will not work with a low powered amp, or a speaker that has a very low impedance, may severely tax the power of an amp that does not double in power as the impedance is halved.)
My two cents worth anyway.