My new Accuphase 408 is lacking ......

How new is the 408? that would be a starting point to help with some possibile solutions.

Well I have asked the dealer in the UK, and he said it does not require a long burning in period(they suggested 10 hours), do you think I should change the speakers??
has any one tried the integrated E 408 with Proac D25 ??

what AC cable are you using? I was somewhat disappointed with my $10K Accuphase C275 pre until I began experimenting with upgrade cords. Settled on the Synergistic Research Designer Reference Squared AC X-series with active shielding (I think they call it the Absolute Reference now?). Esoteric equipment deserves esoteric cabling anyway.

I would still give it more time to burn in and settle before you start to change (even though I agree with (Bob_bundus), it migh be a "synergy" mismatch for you. If you decide to change ac cable as always if you have a chance to audition first it would be even more helpful, but try your more budget oriented change before a "heavier one" there's a lot of variabiles you're still working with. good luck and keep posting if you don't find it right off.

thanks folks for your help, Ill give it a try...