@audiostick Amp shopping, for me, was about 3 or 4 years ago, now. So, I'm not sure which Luxman I spent time with. If I recall correctly, it had pale yellow VU meters. So, I guess that would have been either the L-550 or the L-590. My short list came down to either the MAC MA5200 or the MF6si. I would have loved to A/B both of them in the same sound room with the same equipment but, alas, that wasn't possible. It was a difficult decision. They are both great amps. The sound room I A/B'ed the Luxman and MAC in was more like my sound (living) room at home. The sound room I auditioned the MF in was much larger, had higher ceilings, hardwood floor, brick walls and was like and old refurbished factory building.
With respect to the speaker placement issue, I do not believe the ML Motion 60XTi need to be placed that far away from the wall behind them. I think 2 or 3 feet would be sufficient in this regard. What I was referring to was the space behind the listening position (i.e. space behind your head). I've read reviews of speakers with AMT tweeters where the reviewers actually recommend a good amount of open space behind the listener so as to avoid listening fatigue. In other words, if your listening position is, for example, a couch up against a wall immediately behind it, this might not be a good thing. I actually did do some serious seat-time with the ML Motion 60XTi in two different shops. One listening room had a wall approximately 4 or 5 feet behind the listening position. After about 30 minutes of music at concert levels, my friend and I started to develop noticeable headaches (listening fatigue). After about 45 minutes, it was time to switch to a different pair of speakers. However, this shop used a 60 watt NAD integrated that I think may have been a Class D design. This might have been a factor, as well. The shop that my friend and I auditioned the ML Motion 60XTi in that used the Simaudio had a listening room with a good 9 to 10 feet behind our listening position. We were there a good 3 hours, if not more, listening to music at concert levels and had absolutely no problems with listening fatigue. We had a very similar experience in yet another shop where I auditioned a pair of Triangle Australe EZ speakers. That shop had a huge sound room with, easily, 20 feet of space behind the listening position, if not more. Amplifiers used there where all MACs. One was a big tube stack and the other was the MA5200.
Hope this helps!