Marantz PM Ki Ruby vs Musical Fidelity M6si

I have narrowed down the options to drive my Dali Rubicon 5s. 
I’ve heard that unlike most marantz reference series gear, the ruby is not as warm. Also, uses a Class D instead of the usual Class A or A/B.

interestingly enough, I tried the musical fidelity m5si and it sounded quite good with my speakers.  It wasn’t as bright as I expected. It was lively yet warm. My budget allows me to go for the next level, so I’m wondering if I should go for the warmer Marantz Ruby or the MF m6si instead. 
If you own either of these amps, plz could you share your thoughts? There aren’t many reviews and really need your help. thanks!

I am detailing the parts in the KI Ruby,,I took a quick look inside and I believe there are 
2 fuses ,I will be replacing them ,one to the power supply , behind the IEC the wire loom is partially blocking it,
and the 1.6 amp T or slow blow ?always buy next size up 1.8 ampT if possible for stock fuses can vary over 15% these high end fuses are accurate and can pop
plus the engineers I spoke with and uncle which  is a design engineer said a minimum of 20% over tolerance is built into the design .
do you know the value of the second fuse? I know one is a 1.6A 5x20mm and I like to replace with Furutech blue fuse. the other one I didn't check yet. So, do you recommend use a 2.0A fuse instead 1.6A
I actually have a PM Ki Ruby playing a pair of Revel F208 and had a MF M6si for 3-4 years playing the same speakers and a pair of Monitor Audio Gx300 before them.

I upgraded the M6si to a Pass Labs x250.5 and then I moved it for a second system so I needed a new amplifier and got the PM Ki Ruby.

I need to say both are excelent, the most important difference is the presence of a very good DAC in the M6si.

I never did a direct comparisson but I remember clearly the sound signature of the M6si.

The Marantz has more bass impact and a little warmer sound. The M6si is flatter with more resolution and shows more mids presence. Again the soundstage o the Ruby is three dimensional and shows a lot of depth and is the first thing you will note. Both are very engaging not analytical in anyway.
The cons of the Ruby I would only quote for a little hi frequency sparkle that bothers me in some recordings. The M6si is less engaging but easy on long listening sessions.

I would like to say that a I struggle with the M6si until I discover the impact of speaker cable on it. I am not a snake oil head but in this amplifier the speaker cable has a lot of contribution for the results.
If I could choose now maybe I would prefer the M6si over the PM Ki Ruby but here in Brazil we have limited availability of eletronics and sometimes the prices got a lot higher than the international prices.
Another point is the aesthetics. The PM Ki Ruby is a wonderful piece of equipment and gives a lot of proud of ownership.

Not sure if anyone is still out there on this thread, but I wanted to post some thoughts. I’m actually the guy that verdant audio mentions going from a Marantz amplifier to an M5SI at the beginning of this thread. The Marantz I had was the PM 14-S1 and the M5SI had it all over that thing. I’m sure my choice of Sonus Faber had something to do with it, but overall the 14-S1 just wasn’t for me. 

Fast forward to now, and I’ve had the KI Ruby set for a year as well as still have and swap in the M5 SI. I think both are great. I’m actually on here right now because I have loaded pictures and started a whole post to sell the M5 SI due to moving and space and all that. I haven’t put the ad up because I’m torn. I really love that musical fidelity amp and I’m trying to justify keeping it even though it’s completely illogical, and I will probably use it less often where I’m going to move.

I’ve never heard the M6 SI but like everyone else I’ve read all over the web that the two are supposed to sound very similar, and one can be a good indicator of the other keeping in mind the 6 would be an elevated experience. The build quality of the musical fidelity is very good and everyone saying it’s built like a tank is very correct. But the ruby set is just in a different league of equipment. The build quality on these is outrageous. I’m sure to those out there who have $10,000 pieces the build quality is normal, but when I unboxed these I was VERY impressed. Impressed like I was talking out loud to myself on how bad ass these things felt to the touch and when you tap on them and when you run your hand across them. Ha! That last part would sound really weird to the uninitiated!

I personally don’t want a built-in DAC in my amplifier, so the ruby fits that bill for me. I think the SA KI sounds absolutely wonderful and especially super audio cd. I will, however, give a quick story of an experience that happened when I did a comparison between the DAC on the SA KI Ruby and my Chord Qutest. I had the SA player plugged coaxial into the Qutest, as well as RCA’s from the SA player into the CD input on the PM KI. The Qutest was in “Line 1” on the PM KI so I was easily able to push one button on the remote to switch the output I was hearing from DAC to DAC. The Qutest was undeniably noticeably more present and more ready to fight, so to speak. and anyone who has owned the Qutest can attest that it sounds fantastic. I could go on about that piece alone, but I won’t. The SA KI sounds great, as I mentioned, but it’s just not quite as sensitive I guess. That might be the word. so sometimes I listen to CDs through the SA KI as a transport to the Qutest, and other times like right now I just listen to the CD player like I did 20 years ago. Both ways are enjoyable to the utmost, and I feel very fortunate to have this equipment.

One final thought before I ask what anyone thinks on me selling the M5SI or if anyone might be interested in it, I have the Marantz TT – 15 turntable and it hooks into the PMKI and plays flawlessly. Whenever I hooked it into the M5 SI there was a constant buzz. It would lower in volume if I grounded or didn’t ground but it was there all the time. I found that very odd since so many reviews talk about how good the preamp for phono is in the M5 SI. I’ve used it in two different homes and used both grounds from the turntable, one of the grounds, no grounds, nothing seems to get rid of that buzz. Thoughts?

Anyone have a good home for a musical fidelity M5SI? Ha ha! Ahhh!

I have owned an M6si for two years now and it's really good, especially for the price. I am using a Mofi UltraDeck with it and it is dead quiet. no buzzing or any noise. The cables you use with it are really important. I am using all Cardas Clear Cygnus with balanced to my Oppo 205. This is one powerful and dynamic amp with detailed, but non fatiguing sound. It also controls speakers with precision. I couldn't be more pleased with it. I'm still trying to decide on adding a phono preamp to it. The built in phono preamp sounds really good with high quality vinyl, but I would like to take it to a higher level. My phono cable is also Clear Cygnus.