Fully agreed with above, but one other suggestion - try running the M60's full range (no receiver crossover engaged) with no sub attached. That will remove some of the variables from the equation. If you go that route you can then try a more direct comparison of your original speakers against the M60's with no complicating factors. Just a thought.
To be clear I am not suggesting you leave the setup this way as the sub will likely help overall sound impression, I was just thinking in terms of making it easier to evaluate your purchase.
