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!

This is a tough call.  I had a customer move from a PM14s1 to an M5si and was pleasantly surprised by the improvement in detail and eventually wants to step up to the M6si.  

I am an MF dealer and love the M6si.  Fully balanced, dual mono design makes it a bit more refined than most, especially at its price.  MF is more neutral than most think and the higher you go in the line, the closer to neutral it gets.  

The Ki Ruby is going to be a hair warmer than the M6si.  It is, in some ways, not quite as refined as the MF in that it is not a dual mono, fully balanced design but is a step up from the PM14s1.

A big question is going to be what sources you are feeding into it.  The MF is at its very best when it is paired with fully balanced sources.  If your sources are fully balanced, it is almost a no-brainer to go with the MF.  If not fully balanced, the Marantz may have the edge or it might be a push in terms of refinement.  Then it comes down to which sound profile you prefer and the fact the MF is $1200 less.  

One other note, although the MF is a bit less expensive, that is driven by it being made in Taiwan while I believe the Ki Ruby is made in Japan.  

I am happy to answer any questions I can and if you settle on the MF, PM me and I will be happy to work with you on the sale.  I accept trades and do my best to make things easy on buyers.  
Thank you. M6si is a strong contender. Will ping you if I decide to go with it.

Nobody here owns either amps, esp the PM Ki ruby? Plz take a min or two to share your experience. I’d really appreciate your help. Thanks guys!
A number of months back I stepped from the Marantz 15S2 series to the Marantz KI Ruby Integrated/CD player.  Unfortunately I have no experience with the MF gear.

I purchased a "pre broken-in" pair and it was immediately apparent they were superior across the board to the 15S2 gear.  The sound stage was more expansive in each direction.  They are more transparent.  More dynamic.  More detailed.  

I have always viewed the Marantz sound as more neutral than warm.  But if it leans in a direction, the gear is always smooth, never offensive.  So yes, maybe a tad warm.

My only disappointment was to find no pre outs on the integrated.  Otherwise, the gear is a long term keeper.  

thanks for the detailed review of the ruby. I don’t think I’ll need the pre out (at least for the foreseeable future). All I care about is getting enjoyable music out of my rubicons. By enjoyable I mean detailed, transparent without being fatiguing. What the rest of your setup? Speakers and source?
I'd like to add my thoughts on the Marantz K1 Ruby as well, though not having heard one. I have the Marantz Pm15-S2b, which Ken Ishiwata used as a model to bring some of the magic he developed on the Ruby series down to the PM15-S2, hence the "b" designation.

Being retired, bored, and in lock down, I swapped out my beloved Kinki EX-M1 with the PM15S2b to see how it sounds now that I have the Audioquest Niagara 1200 power conditioner.

Before the Niagara 1200, the Marantz was a step down from the Kinki. The Kinki had it all over the Marantz in terms of immediacy, leading edge, extension and soundstage size, for starters. It also had more impact down low. It was larger than life.

With the new setup, it's now a sideways move and I'm liking it even better than the Kinki. (Alvin, please don't read this). It now has as much impact down low as well and that organic bloom that follows. Cymbal strikes has more of a burnished, metallic colored sound. It seems that there's more of an organic bloom around everything, which is probably why Doug Schroeder went and swapped out the IC opamps for discreet ones, feeling it raised the bar on what he thought was a cool sounding unit. Vocals aren't as pinpoint and lit up in an isolated way but sound more convincing, as if you were sitting a few rows back in a real venue and not in a recording studio wearing headphones.

Maybe he was onto something. 

Add in more features and the fact that it matches my SA15-S2b SACD player and I may relegate the Kinki to the closet for awhile. One caveat though, and it's something I spoke of a long time ago: use a better fuse, and it doesn't have to be an expensive one.

There was a bit of splash in the upper mods and highs that were a bit distracting, especially with female vocals, brass, and stringed instruments. The Niagara eliminated most of so I went back to my stash and found the one that worked best in it: a Brimar fuse that set me back $25 but is no longer made. That completed things for me. Give the Marantz Ruby a good look if you can get it for a good price.

All the best,
@nonoise thank you so much. This is very useful and I’m glad to know that you’re enjoying your gear. It always feel great when you return to a piece of gear after sometime and it sounds surprisingly better.  Stay safe. Cheers!
relative to the above comments, as I stated the 15S2 and the Ruby are two different amps in more ways than one.  

@prashanth 13485, you can look at my system on this site.  I have driven multiple speakers with the Ruby combo with great results.  BTW, the output of the N-core class D amp goes ballistic into low impedances.  So your 4 ohm speakers will have more power than they can handle (in a good way).
@corelli.. thanks again. Just checked out your photos. What a beautiful listening room you got. 
Wish I had a dedicated room. Mine’s a living room setup so you can imagine the whole host of acoustic problems I am having to deal with. Next up, I want to do some basic treatment but I have to make sure that my boss (wifey) is happy with the decor.  Lol
Thanks for your kind words.  A dedicated room is a huge plus.  But don't despair.  Great sound can still be achieved in a living room. (An understanding spouse goes a long way in this situation)
Ruby owner here (integrated first, followed by SACD player): I’ve been extremely pleased with both pieces, but especially the amp, as I’ve shared in other posts here & on Hoffman’s board.

I did not audition the MF; I’m sure it’s a fine unit.

To summarize, I find the Marantz open, fast, non-fatiguing, with a very good phono section & headphone amp. A little while back I switched in an old iron lung power cord (and a new Amazon sourced hospital grade $15 power cord); I continue to shake my head as to just how good this thing sounds. Believe I’m in for the long-haul with this one, I can squander my $$ on other things now...

Looking at both Rubies together as a system, the convenience of a common remote to control the amp & silver disc spinner has grown on me and girlfriend; she’s comfortable using and enjoys listening to the system. (Think long-term, big picture here..) I can use the DAC in the SACD with a streamer. Food for thought, esp with the prices on the amp coming down.

Hope this helps, feel free to pm me with any questions.
@p3ga thanks for the detailed review. Funny enough, I have a very similar setup. I use the node 2i for streaming but is hooked to a marantz sa8005. I bypass the node dac and what a pleasant difference it has made. Everything is so much more musical and non fatiguing.
I’m fairly clear about the ruby but I’m also getting a decent deal on the PM 10 (still considerably more expensive than the ruby).
Have you had the chance to try the pm 10 by any chance? Is it worth the extra dough or should I stick with Ken’s last work of art with marantz ?
I did not try the PM-10; at the time I was looking, I could not justify it at full tariff, so it never entered the thought process. I'm confident that it offers some advantages over the Ruby integrated, especially at the price delta between the two. I might, however, need to spend a retirement-postponing amount on speakers & peripherals to appreciate the difference between the two.

I hope you have the opportunity to try both and would be interested in your findings. 

@p3ga  guess what.. I got the Pm ki ruby. Arrived yesterday and I have spent a few hours with it.

initial impressions, nothing ( and I mean literally nothing) sounds harsh at even very high volumes. Treble is definitely rolled off but there’s still plenty of detail. Mid range and bass are excellent. Vocals are gorgeous and bass is tight and fast. With the musical fidelity 5si, often times I couldn’t go past a certain point with a lot of tracks before it got bright and fatiguing. Don’t take me wrong, MF is a fantastic amplifier, I was considering going for his bigger brother 6si. Very lively and energetic sound. Very musical too. Was a bit too revealing for my dalis esp when playing tracks with a wide dynamic range.

Anyway, the negative seems to be the flip side of the pro. Everything sounds a bit darker and sometimes unexciting.  It’s too early to come to any conclusion but these are just my initial impressions.  Does this make sense?

what changes do you think I should expect as it burns in?  
Thanks again for helping me pick this amazing and unfortunately, underrated amp. I’m elated even with the way it is right now.

I am done looking for perfect measurements and clinical sound. I just want engaging music and the PM ruby shines on that front. Great work by KI!
Well congratulations on the new addition to the family!

There was some break-in time, I recall more extension in bass & highs after a few weeks. 
In one of the posts above, nonoise mentions power conditioning: I can attest to the fact that the Marantz likes & appreciates clean power.The amp is revealing enough that you should be able to hear a difference in ac cables: A Pangea will make the amp sound dull and lifeless; the Amazon iron lung jellyfish  (<$20) really opened up my system:
There's hundreds of others, I stopped there as I'm satisfied. For now :)

FWIW, I am using the Canare 4s11 speaker wire & Audio Envy interconnects from the Ruby SACD. An Audioquest Powerquest 3 protects all from voltage irregularities. Happy camper here.

Hope you enjoy the amplfier as much as I have mine.
@p3ga funny coz I just ordered the canare 4311 after a lot of research, and turns out it’s your recommendation.

I’m absolutely loving the amplifier. It’s opening up nicely, I can already hear a great deal of difference. Highs and mids are opening up and bass is punchier too.

That $20 power cable really make such a big difference? It’s so cheap that I cannot not try.

different topic, do speakers on spikes sound better than those on rubber feet? I have my Dalis on herbie’s rubber feet coz I have wooden floor. I’m wondering if I should buy those spike feet if they’ll make them sound better. Any thoughts?
my Dali's (many pairs) have always sounded best on Mapleshade brass cones, but the included spikes sounded good too...some prefer no footers...
@jl35 thanks for your response. Any recommendation for feet under the Dali spikes? I don’t want to damage the floor but at the same time don’t want to compromise on sound quality either.  I was consider the herbie’s pucks but there are several options on amazon for a lot cheaper. Having a hard time making up my mind. 
I use the Dali’s into the wood. In other systems I’ve had good luck with Adona brass pucks 
@jl35 i just ordered the Herbie’s puck gliders to use under my spikes. Hope they live up to the hype. Cheers
guys, if you’re using spikes you have to check out the herbie’s puck gliders. Not only do they make moving speakers super easy but also improve the sonics substantially. As far as I’m concerned, this is it for me.

perhaps, I may get a turntable at some point but the rest of the chain are here to stay and I couldn’t be more pleased with the PM KI Ruby. Cheers!
I have a Marantz PM-KI Ruby and I like to replace the power supply fuse and power cable. Somebody knows the oem fuse measures?
I was looking for Furutech fuse and PS Audio power cable.
I already checked and it uses a 5x20mm 1.6A fuse. This Marantz PM-KI Ruby definitely needs a High End Fuse.
I had a $6 k Krell vanguard and bought the Marantz ruby integrated .
i know the musical Fidelity’s latest 6 , it is fast and pretty musical 
but the KI Ruby is for sure more fleshed out and involving especially instrumental 
depth and soundstage depth.saying it is harsh as with all quality equipment these amps take a solid 250 
hours to fully run in ,and for sure use a quality power cord , as well as replacing the 2 fuses in there which is a noticeable step up in resolution .and being in Audio for over 40 years ,observing the matched parts quality is much better then MF for sure the preamp is also active with seperate power supplies ,not passive the KI is a dual mono design direct coupled to the Copper speaker terminals, just look at the pictures,the others use cheap brass connectors also preamp is totally isolated and ,volume is regulated microprocessor much better resolution then the plastic carbon volume pots on the MF and copper chassis is $$ for its anti magnetic isolation they put in over a year designing it and voicing it it is a bit tube like but with SS grip and dynamics 
the Ncore modules put out not the stated 100 ,actual 170wpc into 8 ohms 280 into 4 and the  negative current feedback design truly controls Loudspeakers impedance loads. We played maggi 3.7s to the Amphion  3S monitors with  great control and musicality.Ken Isawata  died last year 
just after retiring after 40:years with  Marantz . This was his last effort,
and a very good one at that.RIP Ken, a true Audio pioneer.
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.

I own the Musical Fidelity M-6Si integrated amp. I am VERY surprised it sounds this good

The Musical Fidelity M6si offers excellent performance, facilities, and power. As per the Musical Fidelity web site “Internally, the M6si is configured as 2 independent monobloc power amps with a separate preamp. It is, in fact, a preamp with 2 monobloc power amps that just happen to share the same casework. The M6si has 220wpc. It has very low distortion, outstanding noise ratio and extremely flat frequency response”.

I am very happy with my Musical Fidelity M-6Si integrated amp since this amplifier deliveries the sound quality I am looking for.