Unfortunately, I had some of the same experience with the XPA series amps, though I had the XPA-3. Boomy inaccurate bass, and a brightness that was an issue. The Parasound Halo A21 was in a completely different class. I think those XPA amps have switching power supplies these days, not great. Also they only spec down to 20 Hz. How many db's down their amps are at 10 hz, your guess is as good as mine.
I would expect the XPA-1 to be better than the XPA-3, though. You probably don't need mono blocks, but I know what it's like to want what you want. A Parasound Halo amp would be fine, or if you're on a budget, the Adcom GFA 575SE, at 350 wpc.
I would expect the XPA-1 to be better than the XPA-3, though. You probably don't need mono blocks, but I know what it's like to want what you want. A Parasound Halo amp would be fine, or if you're on a budget, the Adcom GFA 575SE, at 350 wpc.