Rather than giving a blow-by-blow account and bore your respective socks off - here is a synopsis of what I thought, which pretty much matches that of my compadre:
Sneaky DS vs Majik DSM
What a good piece of kit the Sneaky is, and when using it's own amp, it sounds way better than it has any right to (imo). With all the speakers tested, it always sounded accurate, detailed and fun; as well as loud enough if used with reasonably sensitive speakers and at sensible volumes.
It got a touch ragged at high volumes, with a slight loss of bass control and a little hardening of the sound. It would make a great second system, or even a temporary solution while making up one's mind on an amp. The more bass a speaker was capable of, the more one realized the control wasn't quite there. The front ported Rega RS5 highlighted this on bass heavy music, but being the easiest to drive it could achieve fairly high volumes. So overall, nothing to complain about for the money.
With the insertion of the MDSM, everything improved. There was a greater ease and naturalness. Gone was the slight flabbiness of the bass and hardening up at volume....the extra control was noticeable, along with poise and finesse. In fact, as a result of what I heard, I'm going to have to (somewhat) eat my words on Linn amplification. Matched with the right speakers, the slightly cold, lean and analytical presentation of the amps can be greatly mitigated.
Speakers (In reverse order)
1. Majik 109 - These were pleasant enough, but not exceptional in any area. The didn't do anything to annoy, but also didn't do anything to excite either...a bit Meh.
2. R300 - I have a strong feeling that these would have moved up a place if they had been properly run in. They were almost out of the box, but had around 24 hours of continuous use before we heard them. I could certainly hear the enormous potential in them, and the tremendous scale they are able to deliver (for their size). I would say they would be better all-rounders than the Regas. Being new, I felt they were not yet at full potential.
3. Rega RS5 - I liked these, but imo they worked better for certain types of music, like acoustic, vocal and chamber music. They can produce plenty of scale, have enough life to be fun, and seldom sound harsh or bright. Although they are easy to drive, it takes an amp with with a bit of current behind it, to control the bass.
4. LS50 - It will come as no surprise to anyone who has heard them, that we both loved them......these were the clear winner up to this point. They were superbly balanced, and just played music with consummate ease and insight......they just sounded "right"......a Reference speaker at affordable money, which had just the right touch of forgiveness.
5. R500 - These were the last to be connected up, as they had to be picked up from someone local, who had them out on dem.....and wanted to swap them for the R700s.
From the first note, we both knew that these were the ones we preferred......there was just no substitute for the scale they brought to the music. They sounded fine on the end of the Sneaky, but it took the MDSM to make them sound great...........what an exceptional match they (and all the R series) are with the Linn, as they complement each other beautifully.
IMO. The R Series are so good, that it won't be long till they will have to improve the Reference series.
Conclusion
The R500 was the preferred choice, with the LS50 pushing hard on its heels; but in the end it was the extra scale that won us both over (I have always liked floorstanders). It's just as well the R700s were removed, or his wallet might have suffered spontaneous combustion!
As for amplification, we will wait to see how close the upgraded Sneaky DSM can get to the MDSM (it will be about £1k cheaper)........so we will be back in a few weeks to make the final decision.