I actually did A/B comparison of XPR-1's with MC601's. When played loud, 601's had slight edge on bass definition and overall dynamics, but I thought they were very similar. To a more trained ear, there may be more differences, but I thought the sonic signatures were almost identical.
I am in love with Mcintosh looks, so when I opened my eyes, those blue meters made 601's sound so much better
I ended up keeping a single XPR-1 for center channel, and exercised the 30 days return policy on the other one.
On a blind test, I don't know if I could have really tell them apart each time...
At the time, my system was Krell Phantom III alternating with Mcintosh C2300, MC601, SF Stradivari.