I have tri-amped system with pair of old YBA amplifiers, esp. one driving upper bass/lower midrange (70-700 hz) is the Signature amp with hefty power supply but rated 140 watts at 8 ohms. The range above that driven by YBA 2 delta rated 140 watts at 8 ohms. The sensitivity of the speakers is about 89db/watt. I will try PS Audio Stellar 700 for the midrange and see if it makes any difference.
thanks,
thanks,