It’s been a minute but I had those speakers, I ran them with a Parasound A21, Primaluna Evo 400 integrated, Coda CSiB integrated, Krell 300xd Amp / Krell Illusions ii Pre. The 1028BE’s didn’t sound at all dull with any of the amps / pre combo’s. I ended up moving on because they actually were to intense in the upper regions depending on the track. Hard Rock could be fatiguing. Something either with the speaker, hook up or the Amp / Pre isn’t right. With the BE tweeters, hard for me to imagine they would ever sound dull.
Advice to have a local dealer give them a listen / look is great advice, also having your electronics serviced, bias checked. Could be the gear or the crossovers in the speakers but as someone else commented, for both speakers to be dull sounding, that would be highly unlikely, points more toward the electronics. These speakers were efficiently rated but they sounded better with current, not nescesarily Watts for days but with an amp that put out current that can control, drive the woofers, components.