Matching preamp to amp

CAT rules! It could work either with SS or tubes almost all brands you can ever imagine. The key trick is its low output impedance. Yet it doesn't have the best possible maximum output voltage as it could reach in certain units upto 20V.
If the pre's output impedance is too high compared to the input impedance of poweramp than the output impedance becomes a part of circuit and divides voltage(i.e. eats a portion of such) passed onto the next stage.
Example: if your output pre impedance is 1kOhm and input impedance of amp is 10kOhm than 1/10th part of passed voltage is lost 'without reaching' the input of amplifier.

You shouldn't have any problems driving the D-70 with the CAT. Maximum output on your CAT is more like 50 volts which is the same as preamps from Audio Research.

Rrog, I am not worried about the fact that the CAT has enough output to
drive the ARC, instead I am concerned that it has way too much output.
The ARC is rated at 0.95 volts to drive it to full power... Since the CAT has the ability to drive 50 volts, I am concerned that even the slightest turn of the
volume control on the preamp will overdrive the amp /or the amp will be at full power. BUT, looking at the other responses, I suspect that it will be ok, once the amp is up and running we shall see and if not, then i think Almarg's suggestion should work.

Dave,
More would never hurt. I'm not sure about 50V but typically tube preamps do swing larger voltages than solid states.
I'm SS dude but CAT is on my most tube likes!

Daveyf, Read your question again then read my response. The CAT has the same output as Audio Research preamps that matches your D-70. Actually the ARC SP-8 is a matching preamp for your D-70 and has a maximum output of 60 volts, but you won't be using the 60 volts you will be attenuating your source.

Did you try the CAT and D-70? Maybe you should try it and let us know what happens.