do i change the preamp or the speakers?

I recently acquired a set of Odyssey Stratos Monoblocs (w/ upgreaded cap) which i run through an Audible Illusions 2d with new tubes from AI. This set drives my Kef 104.2's. i use some streaming through an Adcom DAC but mostly i listen to vinyl on my Thorens TD 160 with Shure cart.

Before the Stratos arrived i was driving this Kef's with an older Bryston 3B and it was nice.

The Stratos betters the bryston in all ways but the Bryston was "brighter" and suited my listening tastes better when using the Kef's. This new combination is too warm for me. In fact i find the combo of the Stratos and AI sound better driving my IQ TED 400's which are a brighter speaker. I have also substituted my old NAD 1155 solid state preamp which is not the same class as the AI but the slighter brighter nature and the ability to adjust he tone and loudness for lower listening levels has me switching back and fort between the two preamps.

So the question i have is this. Do i change the speakers or do i shop for a replacement preamp.

if it matters, i am a fan of rock music.