Need integrated with LOTS of WATTS

Sorry guys, I didn't notice he listed a budget when I put in my suggestions. My bad.

Look into the the 60 watt Bryston and the the Creek 5350SE (used).

SS and difficult to drive speakers are not my personal cup of tea (but trust me on this, in your price range :-).

Forget the thou budget @new.
The NADs will get you to the bottom of the power you asked for

I looked up ATC and found the SCM50 in active or passive versions. no '7's.

Could you be a little more specific? Sensitivity maybe? And if available as active OR passive speakers, the amps and power of the actives.
The SCM50, above has 500 RMS divided 250lf / 150 mid / 100 hf.
If you are set up for it, bi amping with 'd' amps would work wonders, if all you want is sheer power.

Usage is something you don't address, either. You'd have to redline these in a pretty large space to TOUCH the kinds of power you are after.

A preowned Krell 400xi integrated? Save up for MAC? the MA6900? is that a right model #? How about a used W4S integrated or the identical looking PSAudio GCC series? Any chance of auditioning something? Do you have any musical goal in mind? What did you hear the ATCs with that made you buy 'em in the first place?
Other than sensitivity, what makes you think they are 'difficult to drive'?

I googled ATC 7, and it looks like the sensitivity is rated for 84dB @ 1W @ 1m. Yeah they are rather inefficient. I used to own Revel M20's with 87dB sensitivity, and they were fine with Classe CAP-151 and Krell 300iL integrated amps. I think you need at least 100W clean power for your speakers, but keep in mind quality is more important than quantity.

BINGO!
Now, any idea what the phase angle data looks like?

And Yes to Jylee. Better watts.....are better!