what speaker cables would you use?

Try LAT International. (www.latinternational.com) I received
their IC-200-speaker cable, and already right out of the box it beat my much more expesnice HMS In Concerto. See reviews on www.audioreview.com Acording to other users, it's as good, or better, than the Cardas, but a lot cheaper.

I know that I am weighing in on this thread rather late however, I'll give it a shot. I too am using the David Berning ZH-270 amplifier and a speaker similar to the Merlin. May I suggest Jaden IC's and speaker cables that are made by Ric Cummins, www.roomlens.com

I have tried many different IC's before (Tara Labs, Coincident, Cardas, Kimber, Norodst Quattro Fil, Acoustic Zen Silver Reference, Silver Audio, Totem, Coincident, etc.), but my favorite is the Jaden because of the cable's superior tonal balance, detail, smoothness, bass control, and coherency. Since employing the Jaden's in my system, I've never desired to use another cable.

Check-out the series of speaker cable reviews by Bob Neill on:
http://www.positive-feedback.com

Another Speaker cable and interconnect to check-out is Ridge Street Midnight Silveredition. A real some what unheard of (at least to me), but a KILLER!