Please forgive my post, if this subject has been discussed "ad nauseaum." I searched, and did not see many posts.
While going through the archives for posts on PSB Image 25's, I came accross a post about the impact this center channel configuration can have on overall system sound. The poster, to whom I am QUITE grateful, suggested either using a center identical to the fronts, or a center using only one mid, rather than two.
Given the modest speakers I am considering, is the effect of using say the PSB C40 or C60 going to be that apparent? Would substituing a third B25 as center be a better option? I am also considering NHT SB-3's and Ascend CBM-170's.
Three identical speakers is always a better choice over an O-o-O center speaker. If the speaker line does not have magnetical shielding in others than center speakers, and you need it, then it will be better to get the dedicated center, but be sure it has same drivers than the mains (tweeter and mids, bass not necessarily). In theory the O-o-O center does not have problems when listener is directly in front of it, but if you go sideways from the centerline the comb filter effect might harm the listening experience. So if you use the system alone there is no real problems, but if there's more people then you should try to get an identical front (or place the center vertically).
It seems the B15 is shielded so you should get 3xB15 to the front.