Originally Posted by Ethan Garner
To get less post processing after the dac, and to get the (audyssey xt pro) I was thinking of returning the m51 and replacing it with a m15hd2, and just let that drive the t757 in bypass mode.
I was hoping you all could answer a few questions:
1. Is the dac in the m15hd2 the same as in the m51? Is the M51 better quality?
2. Should I replace the m51 with the m15hd2, or should I run the m51 into the m15hd2?
3. Is all of this over thinking it, and should I just get a better receiver like the nad 787 and plug in the M51?
1. No, they are completely different animals M15 HD / M15 HD2 / M17 and M51. M1x pre-amps use conventional multi-ch or 2-ch dac chips, vs. the M51 is their upconverted PWM conversion thingy. So yes, M51 is going to be the better of them.
Now, the M12 2-ch pre-amp uses the same kind of a converter as the M51. So those two would sound about the same.
2. You should not replace the M51.
3. Adding the M15 HD2 or M17, or even the M12 is not going to help you (IMHO) if you continue to drive the speakers with/through the 757 or even with 787. Only if you also give up the AV-receiver all together, and go directly from M15 HD2 / M17 to power amps, then that would make sense. M25 was great a power amp, and M27 is likely to be one too. Emotivas might also get you there too. Esp. the monoblocks for L/R and multich for the rest.
Maybe M12 and M22 combo, plus your existing 757 might be good. Then you could sell the M51. In this case the connections would be as follows 757 L/R pre-out -> M12 -> M22. C+LS+RS+SBL+SBR speakers would be connected to the 757, along with all multichannel sources.