I have some nice pro channel presets that I generally use for vocals. I'm working on a track that could use some doubling. I've got Waves ADT but when I put it in the tracks FX box in track view there's a lot of distortion which I think is because the signal from the Pro Channel preset (compression, EQ, reverb) is pre- the FX box so the ADT plugin receives too strong a signal. What's the correct way to achieve what I'm trying to do? 

You can right click in an empty space in the Pro Channel and select "Post FX Rack" to change the order.
 
Alternatively, you can insert an FX Chain anywhere you like in the Pro Channel and put your ADT in there.
 
AMB
 

When you use the Pro Channel you should not use the track effect bin but use the Pro Channels only. You can put none pro channel effects inserted properly using the Effects Chain

I wouldn't say "should not" Johnny, but I haven't used an FX bin since we had the ability to drag any plugin into to the PC by way of an Fx Chain

Cactus Music
When you use the Pro Channel you should not use the track effect bin but use the Pro Channels only. You can put none pro channel effects inserted properly using the Effects Chain

So if I put guitar amp simulators into the track effects bin as well as using the prochannel, what bad thing will happen?

Daibhidh

Cactus Music
When you use the Pro Channel you should not use the track effect bin but use the Pro Channels only. You can put none pro channel effects inserted properly using the Effects Chain

So if I put guitar amp simulators into the track effects bin as well as using the prochannel, what bad thing will happen?

Nothing bad will happen. It's designed to work that way and the FX bin can be set to pre or post. I'm not sure what Johnny meant in his replay.

Fx bin is useful for external sends.

There no issue with using both the FX bin, FX Chains, and the ProChannel in any combination thereof. It's just a matter of personal preference really. The ProChannel FX chain lets you intermingle normal plugs within the ProChannel, or you can put them in the track bin and set the PC to be post FX bin or not. As with anything, just pay attention to your signal flow and you'll be fine.

Yea Jon!  Glad to see you, or hear you, or, I guess, read you.

OK I rescind, nothing bad will happen,, but,,  since I started using the Pro Channel I like all my effects in there as you can put them in the order you want, using the Bin would make it confusing to my small brain so I only use the Bin on the Master buss now. Of course there are a zillion ways to do thing now but I like to keep it simple.