I decided to try the 2035 based 4 Pi pro's with the gfa555, rated 200 wpc. With the preamp volume at the 2nd mark, about 9 o'clock rotation, average level was "loud". Dire Straits "On Every Street"...the drum stick strikes have "firecracker" dynamics, almost make you blink. Until you run some horse power into them(the Pi's), you will not truly appreciate how great they can sound. Sam