HT pass through or 2 sets cables?

Great it worked well for you. I have been doing this for over a year now, and have been extremely satisfied.

Home theater pass-through would be best. 2 sets of speaker cables would require either manually changing them when you changed amps, or hooking up a switch box of some sort. You shouldnt hook up 2 amps to one set of speakers at the same time.

You can do what I do, run the LT/RT mains outs from the HT processor (or receiver in your case) to one of the inputs on the integrated. Now select that input, and turn the volume control in integrated to a readily-remembered setting. I and many others I have talked to use 12 o'clock. Now calibrate your processor or receiver. When listening to music, dont even turn on the Arcam. When watching movies, select the input on the integrated, turn the volume to 12 o'clock, and you are ready to go. You can use the volume control on the Arcam as usual.
John