CAD? I used to know a few good stores downtown on Queen St. in TO - but that was many years ago, they’re probably all long gone…
Basically what I ended up with was a stock Lenovo Thinktank E31 with two Intel SSD drives added plus an Nvidea graphic card (to support dual monitors VGA and DV). Apart from the acknowledge software bugs, I haven’t had a single issue with Steinberg SW/HW, nor any other SW or periphery I use. (touching wood now 
)
Maybe that will help you if you’re looking for directions.