i decided to contact john regarding having my xa2 amplifier upgraded after a recommendation from a fellow enthusiast. john kindly answered several questions on all aspects of hi fi concluding with the sonic upgrade to be expected once my unit had been upgraded. within 8 days my amp had been picked up and returned looking like a brand new unit. after 250 hours use, everything john had promised has materialized. my system now sounds clearer, with better separation with a fuller yet more tuneful bass. the best aspect of this upgrade is i can now hear new low level sounds on all my cd’s which simply were not present before. if you have any doubts regarding johns service simply ask yourself this question. calculate how much or how little your current kit is worth 2nd hand, add this to the cost of the upgrade and ask yourself can i really buy a better new component for the same price ? the answer will most probably be no. johns service has enhanced the sound of my system, not merely changed it, which is what you can expect if you purchase a different unit. i am now planning to have my x ray cd player upgraded next once funds available. overall excellent.