I hesitated writing this review because my system is bi-amped and I only use the A75 for the mids and highs. However the results are so good that I feel compelled to write a review, just understand that there will be no mention of bass performance.
The system is not your usual hifi system. The speakers are high-end DIY and the electronics are a Roon Nucleus end point, the MiniDSP SHD, the A75 and a high power (450 watts per channel) Class D amp. The speakers use a compression horn, a 10" mid/woofer and dual 15" woofers per side. This is an open baffle design.
The system has been up and running for a little over 6 months. Being an audiophile, I've thought of next steps, but have come to the realization that there is no upgrade path for this system. The resolution is tremendous; all you hear is the recording. If the recording is bright, you hear it. You know where the mic(s) are placed. The soundstage depth, width and height varies with the recording. The center channel image is strong and placing instruments and singers within the soundstage is easy to hear and locate. Sometimes you can even hear an artist breathing hard as he/she plays. All the details are there.
And that is the double-edged sword of resolution. This system, of which the A75 is a big part, simply soars with good recordings. I could not ask for more. However...on lesser recordings, all the flaws are laid to bare. Not harshly, but they are there. This system will not hide flaws. As a result, I mostly listen to well or very well recorded music on this system.
My wife, who is not an audiophile, on occasion, will ask to listen to a song she likes on my system. The first time, she was asking why certain instruments just cut out abruptly. I explained that this is the way the song was mixed and the engineer never thought anyone would hear it. The second time, the recording was so bad neither of us could stand it. She said the song sounded better on her iPad. She played it for me on her iPad and she was right. You could rock to the music with all the flaws in the recording well hidden.
The A75 is a surprisingly high-end component for its price and I doubt that it would hold back any high resolution system. The highs are well extended and not harsh and the midrange is deep and rich. But it will not hide flaws in the recording or the choices that an engineer makes such as having a jazz ensemble with the instruments separately mic'd and the bass player who was on the left is now center stage because his solo has come up and the engineer switched to his mic, collapsing the soundstage.
We all have music that we love that is just not well recorded. You will find yourself listening to that music with a lower resolution system that does not capture the flaws in the recording. The A75 is a worthy addition to a high resolution system. But it can be a reminder that sometimes you just don't want a system this good.