Funny to read your post because I just added a REL T7i to my system. While I'm still tinkering with the settings, I agree that it fills in the bottom end and enhances the sound stage. I have repeatedly read that Harbeth's are difficult to pair with a sub, but so far I have found that it blends exceedingly well. I still think that a more powerful amp might give the sound even greater presence, but so much of the feedback I've received throws water on that idea. I still think the idea of how much power is never explained well. I have considered amps by Audio by Van Alstine (either the Vision SET 400 or the hybrid) or the Rogue Audio Dragon. I'm going to think on it awhile since I would like to get comfortable with the new subwoofer addition. Good luck in your search and let me know if you find something you think is better.