i had both at the same time and the mach ones don't even compared to the forte ll the forte had much better and tighter bass and cleaner sound like every one said the mach ones arent even in the ball park with klipsch forte ll
i have a upa-7 and my nephew has a xpa3 and we did a ab compairson and we couldn't tell the difurence between the 2 the upa7 is a great amp i think and with the sale going on you just cant beat it
that is how i like mine to i did the same comparing the two like you did and ended up going with 400hz/4500hzi thinks its sound alot more natral espsecially in the cymbals