B&W DM70's - top end lacking

Hi  ct0517
Thanks for the reply.
These speakers are something special.
I have the original MK1's.

My room has stone floor (with thick fitted carpet) and stone walls.
I would say that the room is heavily damped and has very low ceilings.

The change of bass unit to the 13 in Leak Sandwich has helped quite a lot.
I was using a Quad 306 as my power, but that could not control the bass at all and in fact the Art Audio is much better in that regard even though it is not so powerful.
It has the option of Ultra Linear at 25 W with variable feedback
My volume requirement is not so loud these days.
One of the reasons for changing to the tube amp is just how much more musical the system sounds especially with Blues and Jazz.

I just want to tame the bass a bit and get the treble balance right.
Sometime I wonder if I have sometimes a voltage problem, as about 80 homes were just built near me in our small village.
The mains transformer did blow up about a month ago and when that was replaced I seemed to get louder treble.
Is it possible that I was not getting enough voltage to the Electrostatic panel? 
The treble sometimes seems to go down a bit at peak times.

ct0517
I see how you have raised your speakers and I did think about doing the same. On my speakers it could be done between the existing stands and the main box, say 6 inches (15cm) should do, I think.

It is strange, as this evening, most of the bass issue seems to be gone. The treble is right up which what makes me think about checking my mains.

Have you ever noticed your speakers sometimes sounding much better than at other times?

iscm -  I found the panels sounded best at ear level and by raising the speaker to achieve this, the bass improved as well. I have a device that gives voltage readout. Plugging components into it also shows how much voltage they are using. Any voltmeter can be used to check AC voltage on the mains. When it sounds good and when you notice a problem. If there is a difference that tells you something is up with your main. But if the mains voltage is good both ways, I would suspect an issue with the power supply in the cabinet so it should be looked at. That is not a difficult repair.      

ct0517. Tonight everything sounds good, although I still think that the treble is a bit recessed.
Did you make your own super tweeter?
I was thinking of using a ribbon crossed over at around 8 kHz with some sort of pot for adjustment. I presume that the effect should be subtle. 

Did you make your own super tweeter?

iscm

the one in the linked picture is a simple dome tweeter. On the (plus +) side of the line there are 6 or 7 resistors.  I add / subtract resistors to get the desired effect, if needed. Very subtle. The curtains that can be seen in that room can be slid open to reveal pine walls and drywall, removing damping as needed. I have tried both the Music Reference RM10 and Rm9 Tube amps with them, as well as an assortment of SS amps. They were quite a load for the Rm10. They sound great with the Rm9. Well, everything sounds great with that amp.

My DM70 are not hooked up right now but your thread is making me want to hook them up, upstairs. :^)