Music Hall 15.2 vs. 25.3?

After looking at several DAC options to pair with a Cambridge Audio CXC transport, many reviews herald the warmer sounds of these units. Since I will be running either of these through an Audio Research SP16 tubed preamp, I thought that the Music Hall 15.2 or the 25.3 DAC might be a good pairing. I would appreciate your thoughts on either of these 2 DACs. Also, am I correct in assuming that the fundamental difference between the two DACs is that the 25.3 is tubed?Thank you so much.