I would estimate that you can get ballpark 100 dB on peaks at the listening position with the 989 and a suitable amplifier. But that's driving the speaker pretty hard.
If you treat the backwave (either with diffusion or absorption depending on your room acoustics), you can probably use the 989's in a 10 by 12 room. I have a Sound Lab customer who is using a pair of smaller Sound Labs (U-2's) in a room that size. No it isn't ideal, but it works. Another customer used full size Sound Labs in a 12 by 12 room and was quite happy. But you have to be willing to treat the room.
In my experience, electrostats like lots of power, but quality is more important than sheer numeric quantity. I've seen 800-watt monoblocks shut down trying to driving Sound Labs to volume levels that high quality 100-watt amps reach with ease.
Regading the Jeff Rowland Model 10, I have no personal experience. Jeff Rowland used to have a pair of Sound Labs among his reference speakers, but I don't know if he still does. My personal experience with amps using digital switching power supplies has been disappointing (lack of dynamic contrast), but the Rowlands may well be the exception to this trend - Jeff is an excellent designer.
I know of several people using TacT room correction systems with electrostats, and they are happy with the results. I see no reason why it wouldn't work well with the Quads.
Personally, I prefer the Quad 988 to the 989. I know you didn't ask about that, but thought I'd throw it out. I find the 988 to sound more balanced and coherent overall.
Your questions seem to imply that you're hoping to get high volume levels from the Quads. If that's true, rather than pushing the Quads to their limit, would you consider the InnerSound Eros? I'm not a dealer for InnerSound speakers, but they can easily play at very high volume levels. They do have a narrow sweet spot, but then (speaking as a former Quad 63 owner) the Quads pretty much have a one-person-wide sweet spot as well.
Best of luck to you on your quest!
Duke LeJeune
AudioKinesis
If you treat the backwave (either with diffusion or absorption depending on your room acoustics), you can probably use the 989's in a 10 by 12 room. I have a Sound Lab customer who is using a pair of smaller Sound Labs (U-2's) in a room that size. No it isn't ideal, but it works. Another customer used full size Sound Labs in a 12 by 12 room and was quite happy. But you have to be willing to treat the room.
In my experience, electrostats like lots of power, but quality is more important than sheer numeric quantity. I've seen 800-watt monoblocks shut down trying to driving Sound Labs to volume levels that high quality 100-watt amps reach with ease.
Regading the Jeff Rowland Model 10, I have no personal experience. Jeff Rowland used to have a pair of Sound Labs among his reference speakers, but I don't know if he still does. My personal experience with amps using digital switching power supplies has been disappointing (lack of dynamic contrast), but the Rowlands may well be the exception to this trend - Jeff is an excellent designer.
I know of several people using TacT room correction systems with electrostats, and they are happy with the results. I see no reason why it wouldn't work well with the Quads.
Personally, I prefer the Quad 988 to the 989. I know you didn't ask about that, but thought I'd throw it out. I find the 988 to sound more balanced and coherent overall.
Your questions seem to imply that you're hoping to get high volume levels from the Quads. If that's true, rather than pushing the Quads to their limit, would you consider the InnerSound Eros? I'm not a dealer for InnerSound speakers, but they can easily play at very high volume levels. They do have a narrow sweet spot, but then (speaking as a former Quad 63 owner) the Quads pretty much have a one-person-wide sweet spot as well.
Best of luck to you on your quest!
Duke LeJeune
AudioKinesis