Doug, welcome. First, you don't have to be concerned about a "match" between components of at least reasonably high quality, which yours certainly are. There are rarely any compatibility problems between components. As to the 895, you should study the manual, but my recollection is that it had a fixed 100Hz crossover, which may be slightly higher than the commonly suggested 80Hz, but is okay. One thing that you should change is that instead of setting the internal sub crossover at the 80Hz mark(which might not be very accurate)you should instead set the crossover switch on the HGS10 to out, which completely bypasses the internal sub crossover. Since the 895 is handling the crossover duties, the sub crossover would just be in the way.The sub output jacks are for a different type of connection and aren't used simultaneously with your present connection, which is better in most cases.
The M5s should serve adequately as surrounds, but users are very impressed with the sound of the Axiom QSs, which you might consider.
