I have an opportunity to buy a used MX5000/MDA5000 combo but was wondering if the MDA5000 external DAC is only beneficial when playing HDCD encoded discs... or will there be noticeable gain in SQ with the amp-sized unit just playing regular CDs?

I am not interested in useless (to me) gadgets or other processing capabilities. I just want a top quality, iconic CD headunit like the Mcintosh that does its job well. If you have heard this combo in a well tuned environment and system, please share your thoughts. Much appreciated.