In September 2023 edition of The Absolute Sound magazine, senior reviewer Paul Seydor takes the pair of Harbeth's M40.3 XD to his reference system for longterm detail listening.
Some of the his observations read quite impressive:
There is no doubt reviewer Paul Seydor finds Harbeth M40.3 XD to be the reference loudspeaker: "I had both the 40.2 and the 40.3 in house at the same time, I can assure Monitor 40 fans that Shaw has made no attempt to reinvent the wheel of what is obviously a very successful and highly regarded loudspeaker. "
"I personally went for the 40.3 XD because I like the change..."
"I got one of the flattest, smoothest most linear responses at one meter I’ve ever measured, almost textbook."
"...as I’ve already indicated, the 40.3 XD has effectively shed virtually all the midrangeyness as such, mild as it was, of its processor without losing any of its much-loved drop-dead gorgeous midrange."
Read the full review on The Absolute Sound