I have heard both the M5 and the Q3. These were in different dealer systems and about two years apart, so I think any comparison from me would have little value. I can tell you, however, that the M5 sounded like a bigger version of my Mini 2. Very coherent, great tone, great detail. Very convincing IMO, especially on symphonic music. Very good speaker, but large and hard to drive.
However, compared to those, the Q3 is just better. Even less cabinet sound. Very little sense that music was coming from a speaker. It just disappeared. Ultra clean, clear, transparent and effortless. If my room could support the Q3, and I could afford it, it would be my next speaker. I still remember that demo at Goodwin's High End and it is perhaps the best demo I've heard. A very special speaker in the right system and room.
However, compared to those, the Q3 is just better. Even less cabinet sound. Very little sense that music was coming from a speaker. It just disappeared. Ultra clean, clear, transparent and effortless. If my room could support the Q3, and I could afford it, it would be my next speaker. I still remember that demo at Goodwin's High End and it is perhaps the best demo I've heard. A very special speaker in the right system and room.