Rgs, I have always been attracted to revealing and transparent speakers. And as an old owner of ML Quest I can say the A9 is on this category, and very close to the Quest midrange (and much better on some other fields). I hope you'll have the opportunity to listen to the A9 on a store or show. I believe you'll realise they are quite revealing.
But before all, the main quality you'll finally remember is the seamless integration between all registers from bass to treeble and the almost infinite range of timbers and colors from one CD to an other.
I've noticed this brightness in the store after 20/30 mins of listening (paired with vahallas) and at home with different elements.
I used to have bright cables (AZ Silver ref) and when I upgraded to the Absolutes, the aggressivity was gone. They will show any unbalance in you system.
They are also quite easy to drive, which may be also a other difference with previous Spendor speakers. I don't have any experience with previous models, but every person who have seems to confirm the people in Spendor did something quite new with this one.
Finally, here is a quote from a review (HI Fi+ 77):
"A few issues back, I waxed lyrical about the Magico Q5. Sadly, not everyone has the amplifier girth, the room width or length or the wallet depth to cope with so demanding a £65,000 loudspeaker. What happens for the rest of us? The Spendor A9 happens. It gives you a lot of that Q5 sound for nigh on 1/13th the cost, and doesnt need a powerhouse amp or a stateroom to hold court."
http://www.avguide.com/review/spendor-a9-hi-fi-77?page=1
I had the luck to listen to the Magico V2 on the same day and same store as the A9. It also also occured to me they were quite close to the V2 in terms of balance, linearity and richness, this time for 1/3 of the cost.