I only have experience with the McCormack DNA-1, but I just jumped to it from an Adcom GFA-545. The difference really is astounding. My 4-ohm Polk LSi9 speakers are completely transformed by its low-impedance capabilities. Got it used for a good bit less than $1K.
It's already in the hands of SMc Audio, for a Silver upgrade. Using the 545 in the interim. I miss the McCormack.
It's already in the hands of SMc Audio, for a Silver upgrade. Using the 545 in the interim. I miss the McCormack.