I'm not sure if I'm following the OP completely. You're using the McIntosh D-150 as a DAC and running into the Rotel RC-1572? Or not using the RC-1572 and running the D-150 as DAC and preamp into the Rotel 1050? Doesn't the Rotel RC-1572 have a built-in DAC? Have you tried using that instead of the McIntosh DAC? Is the sound still too bright for you?
I had a McIntosh MC152 for a couple weeks to demo. It sounded nice, gave a little of that McIntosh sound, but I didn't feel it was worth the price. Was better than the direct coupled amp in the MA352 integrated, but did not stand up to the MC462. A lot of people think the modern McIntosh sound is this warm, tube-like sound. Not really. Their tube amps don't even really sound like tubes.
I own both McIntosh and Rotel gear. I would look at the 1582 MkII over the MC152. You could even go with the big boy, RB-1590 and still come out almost $2k ahead over the McIntosh.