Quad 989/2905 all around qualities

As far as the Klipsch La Scala goes, they are very bright, forward and aggressive. Bass is not very deep. They are a power speaker, quantity over quality. With mods they can be very good but for $6000 I'd take the Quad.

Legendary Sound Labs are the only thing that will top the Quads, but you MUST have the room for them and they will not tolerate cheap gear. Sound Labs go deep and throw sound wide so room treatment is a must. You will, however, be rewarded in spades with a soundstage and depth like nothing you have ever heard.

Do you feel like the ESL2805 have enough bass ?
I would expect it to be very similar to 988 and theoretically to 63 in the low end because they still use 4 panels (no extra bass panels, those only added to ESL2905 or 989)

To my ears they sound very, very similar in all respects. The 988 was an updated 63 with better electronics. I don't own the 63s but have heard them repeatedly. I have not yet had the chance to hear the 2905, unfortunately. Some people experienced quality issues with their late model Quads, but then again the earlier ones were not immune either to their foremost British design and craftsmanship flaws...

The big thing with Quads is they don't last forever, now with shops cashing in the their marketed reputation form years ago. They "someday" will need to be repaneled, keep this in mind because it's not cheap from a refurbisher, (despite being a simple and cheap precess that takes nothing more than a couple hours once your jig and expander/stretcher are in place).

Given the choice at this price point, I would buy the new Quads, 2805 or the 2905 (like I say, haven't hear this bigger model).

I felt that ESL63 doesn't have enough bass and not enough slam/dynamic range to play the rock to my satisfaction. And i am not talking about crazy SPLs or hard metal rock. That is the reason i am prompting to bigger (hopefully more dynamically and more bass oriented) 989/2905; The difference in price tag between 2905 and 989 is huge. It seems a common ground that 2905 is a better speaker than 989 (more refine, yet better slam and better bass), but it is difficult to measure whenever it worth the additional 3-4K$
That's why i want to start from auditioning the 989 and see if this direction will lead me somewhere. Probably i will found out that even with additional bass panels the results with rock are less to my test and that the difference with ESL63 is not that huge...

QUAD reliability problem is indeed an important point...