**HELP** FOCAL ELECTRA 1028Be sound issue (muffled)

Check your 50 year-old amplifier for DC offset and the correct bias. One speaker muffled, yes -- the internals are suspect. But both? Sounds to me that the drivers aren't travelling their full excursion.

I have Electras and do not have this issue at all.  Mine are sweet as can be.  You might need a higher current amplifier.  

I normally run mine with an AEC (Cary) tube amp.

they may not be my cup of tea,but the severe symptoms the OP is having is _NOT_ normal for those speakers. 

That preamp and amp date back to the mid to late 1970s. Have you ever had them serviced? That's what severe crossover distortion sounds like when the amps semiconductors hand of the A and B part of the signal to one and other. Probably something a qualified tech could easily fix and you might have to have some electrolytics replaced in critical areas. Hope is not lost though.

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.