Help using integrated as power amp

If the T747 has tape outputs you could run those into an AUX input on the Arcam and then use the volume control on the Arcam. It should be simple enough.

Whats wrong with the preamp in the Arcam?

If it is the tuner section section in the receiver you wish to still use from the receiver, use the tape output of the receiver connected to a line input of the Arcam.

The pre-amp section of the Arcam integrated would certainly sound better with a good quality source than the pre-amp section of the T747 Receiver. I have owned the same T747 receiver myself, and any Arcam integrated amp will sound better than the T747 does by a long shot, unless you don't like to hear detail, dynamics and clarity in your music....

I bought the 747 because: one, I wanted to be able to use it for watching movies and two, the input selector on the arcam doesn't work anymore. It will work for a while and then the sound will just drop out. When I spray deoxidizer on it that helps but never solves the problem. I was thinking of buying a NAD C275 power amp and running the front speakers off that. Do you think that will improve the sound quality from the 747 or do you think my best bet is to buy another integrated(used). Unfortunately, my budget for that would be less than a 1000, ideally even less than that, as I want to first buy a totem storm sub and center channel.

Any idea how much $$ it would cost to fix the switch on the Arcam?

adding more 'stuff' won't help, if you were satisfied with the original gear.

Maybe 2.1 for HT? works for me, without additional complexity.