I might have to ask, WHICH Mac model are you referring to? Like any company, Mac has made many designs, some tube, some SS, and have done so for many years.
In my experience, I have rarely heard the honesty that the Q is capable of. Any upgrade will change that basic quality, for the better or not. In it's stock form, I have no apologies to make for it, regardless of price. Having said this, I prefer my own flavor in sound, and certain changes lead me there. After 40+ years of experience, I have rarely been so satisfied with a product, let alone so surprised.