Arbuckle, your Pass INT-150 is a great sounding intergrated amp, but it would be unfair to compare its sonic performance to any of the XA.5 series amps which are on a quite higher qualitative sonic level then the X or X.5 series. I hope your tax return is indeed a very big one, the XA-100.5's retail for $16000.00 a pair. I believe that your speakers are a relatively easy to drive, so you could try the XA-30.5 which sounds terrific and would be a pretty vast improvement over your INT-150.
