Anyone used Mapletree Line 2CRM preamp with NAD power amp?

No experience pairing my Mapletree preamp (which is a wonderful piece) with a NAD integrated, but did try pairing it with a different integrated. The Mapletree did not improve the sound extensively until I paired it with a separate power amp. Information at the time led me to believe that while combining a preamp with an integrated can technically work, it is far from ideal based on the way the integrated was designed, which was to work best within its own integrated circuitry. My point being, you likely cannot fairly judge the Mapletree, or any pre, when you combine it with an integrated. If you are going to have two pieces, best to have two separate pieces (pre and power) and use them per their specific optimal design intent. So if you have even a little improvement with the Mapletree and integrated, sell the integrated right away and get a power amp.