Mcintosh MC402, Krell FPB 600 or Passlabs x250.5

Hi guys, need some advice on the above power amp option.

I'm currently using a pair of Sonus Faber Olympica II. It was placed in bedroom and only driven by Krell 400xi.

Now the setup has been moved to living hall and I'm getting a pre-power amp to drive the Olympica II as the krell 400xi obviously doesn't have enough juice. I've tried it with krell 400xi in living hall and the bass extension is just not there, even though I do like the soundstage, smooth mid / high that the 400xi is able to produce with the olympica.

Recently I came across a used Mcintosh C40, and it was always in my wishlist to one day try the mcintosh gear. I bought the C40 and now looking for a power amp to pair with it. Naturally, it would make sense to match Mac Pre with a Mac power, but I would like to open up for more option.

I know each of those three are distinct in their power rating, but I don't always listen at loud level. I listen to all genre of music, but probably spend more time on vocal songs.

Does anyone have experience pairing them with Sonus Faber with great result? In fact all of them cost about the same (I found used unit in my local dealer). Or there's other candidate that I should consider also?

I had the 250.5 and the 402. I'd say if your not going to run the Pass in balanced mode, don't get it. It was horrible in single ended mode. The 402 is a very nice amp. Full bodied and not aggressive, but not tube-like for what it's worth. I'm not familiar with the Krell.
I'm currently using a pair of Sonus Faber Olympica II. It was placed in bedroom and only driven by Krell 400xi.

Now the setup has been moved to living hall and I'm getting a pre-power amp to drive the Olympica II as the krell 400xi obviously doesn't have enough juice. I've tried it with krell 400xi in living hall and the bass extension is just not there,

What is the difference in room volume - bedroom versus living room ?

The speakers are rated down to 40 hz but I can't find a graph to show how the much DB drop to make 40 hz.
How have you tuned the port - is it open or closed ?
Hi Roxy54,

Thanks for the reply! Yup my heart is leaning towards the 402. For the Krell FPB600, I had heard it in the dealer's place but not with a SF speaker, but with two other speakers. I would say with the wrong type of matching, it may really sound 'harsh' for my liking. Surprisingly when it switched over to the other pair of speakers (I can't remember the name) it became full bodied, mid and high became much smoother. Thing is the FPO600 is also pair up with a krell kct pre amp. Still a bit too little 'aggressive' to my liking where I prefer a bit mellow / easy listening setup.

I do not have a chance to listen to Passlab yet. What if i'm able to run the passlabs in balanced mode? Would it be much better than the MC402? But if the Pass more analytical type then I would probably look else where. Seems to be a safer bet to go with the 402.

Hi Ct0517,

Thanks for your reply! The living room is about 16ft W x 30ft L, while the bedroom is only 15ft W x 10ft L. For Olympica II the port is kinda special, it is single-side port located at the back end of the speaker, in pair you can either setup facing each other (inward) or facing out (outward). Fancy name from their website would be "side-firing vertical reflex ports covered by a perforated metal sheet", but I have to admit that it looks kinda cool and nice with the speaker design.

As of now I'm facing them outward.
Hi Nicholas
imo the reason your living area is bass shy is due to the amount of space you are asking your speakers to fill.
Your speakers were able to pressurize your bedroom area without issues.
Without knowing how close you sit, how loud you listen and assuming a ceiling height of 8 feet.

Living Area - 16w x 30L x 8h = 3840 cubic feet
Bedroom Area - 15ft W x 10ft L x 8 h = 1200 cubic feet

So the space that needs to be filled has more than tripled.

so? here are a couple of thoughts.

your speakers are a 4 ohms design, have a 50 - 250watt amp rating (without clipping.)
Your Krell 400xi puts out 400 watts at 4 ohms. So it should be enough.

If you are happy with the music and it just needs more bass to fill in the lower octaves I would be looking for 1 or 2 active subs instead of an amplifier. The other option is more full range speakers; but then with this route you may need another amp is well. you a couple of things to consider...Hope this helps.

if I may ask you how much your dealer is asking for the fpb600. Curious as I happen to own one.

Hi Ct0517,

Yea the bigger space definitely plays a part.. I'm sitting like 7-8fts from the speaker, and both the speakers are 8fts from each otheres with a bit of toe-in. It is like a triangle..

To be frank I actually like the sound from 400xi, but I will be using it for my bedroom setup which is now replaced by another pair of smaller sf bookshelf, that's why I need to get another amp too, sorry for not stating it earlier.. For the additional subs, will it cause more complication (to match with the speakers?) But again thanks for the suggestion..

Just an update on a short audition that I had at the other dealer's place with the mac 402. it was a C39 + 402 combo driving a pair of Revel Ultima Salon 2. No proper setup but more like a quick plug & play for a short audition. Surprisingly the mac setup was not 'slow' at all like some had mentioned previously (maybe it is their newer generation)? I did miss the full bodied low end and the punch from fpb600, but the 402 is not too bad too, just probably more polite. I did like the mid from mac better, meanwhile I think both are doing quite good on the treble / higher pitch note.

Won't have chance to listen to the passlabs but i guess it would not go worng with either the mac or krell since I guess both are quite good in their own league, just down to own preference..

Back to your query for the fpb600, my location is not in US, but it is around US$4.6k after conversion, while the 402 and x250.5 is slightly cheaper..
No decision to make. Go with the McIntosh MC402! You will never regret it.
Hi Mattmiller,

If nothing goes wrong, guess I'll pull the trigger soon.. for the Mac :)
Good call , you will love it !

I like both Pass and Krell amps, but I don't understand why McIntosh uses autoformers with their ss amps? The use of which compromises the advantage of linear frequency response that can otherwise can be inherent in ss amps with typical speakers.

Nicholas_1213 hi
Unsound is correct about the Mac.
It would be good to get hold of a impedance/phase graph of your speakers, this will then give a good idea for either the Krell or Pass. If your speakers are a hard load then the Krell would be the way, if not then either would do and will depend if you like Mosfet sound (Pass) or Krell sound (Bi-Polar).

This is mostly but not always the case depending on circuit and speakers.
Mosfets tend to be sweeter more laid back.
Bi-Polars more punchy and up front, can be just as sweet with lots of Class A bias.

Cheers George
Hi Unsound & George,

Thanks for your input. Yup I have read it on other forums as well regarding the autoformer. I guess it is either you love it or you hate it? If not looking from the technical perspective, I actually kinda like how the MC402 sound compared to the krell (no chance to listen to the Passlabs yet). The krell is impressive, full bodied, impressive punch and bottom end, smooth and detail sounding, but the mc402 sounds more 'relaxing' to me while not sacrificing those quality such as soundstage, details, transparent (yes to me it is quite neutral, non tube-like / coloured sound at all), and it is not SLOW at all like some have claimed the Mac amps are.

Probably at the end of the day when return home from work, I would find Mac sound to be more appealing. Krell is very strong competitor, and the fpb600 that I listened to, is not 'harsh' or 'dry' at all (again like what some other forumer have claimed to be). I would love to have the bottom end (bass) quality from krell to Mac, but guess we cant have best of both world (probably with much higher cost?) If I further add in durability factor, I guess both of them shouldnt give too much problem? Even though the krell class A runs much hotter..

For Passlabs, i have heard all good thing about Pass, but it is unfortunate for not having chance to listen to it. Over here it is also much rare item in used market compared to the other two..
^Perhaps, Threshold, Rowland, or c-j ss as might be suitable options?
Hi Unsound, it is extremely difficult to come across those brand in the used market here.. especially Rowland.. probably those are keeper and nobody would like to sell it away..
^Where are you?
I am pretty familiar with Krell amps. If I would hazard a guess, I would say the FPB 600 would be a better match with your Olympica 2's. If you could get a c or cx series FPB, it would be smoother up top. The predecessor of your speaker, the original Cremona's were a great match with the Krell FPB's. I believe the Stradivari's were voiced with the FPB 600. I have heard the Olympica 2's and they seemed like a different presentation to the Cremona's - more extended up top but losing that Sonus Faber magic. For that matter, the newer Krells are a different presentation too - they ain't got that bass slam anymore but are less strident on the top too.
Hi Mikey8811,

Thanks for your input. Eventually after listening to both, I actually went with the Mac. I don't mind to sacrifice the low end from Krell for the overall much relaxed presentation from the MC402. Ya the Olympica 2 has different taste from their older model, but overall I like the changes, to me they are more transparent / neutral..

I guess it is same for the MC402. Compared to older Mac, it is kind of different taste, but overall in good way. No doubt the 'magic' from older Mac & SF is still very tempting, but i think both new designs make it a better all rounder for more type of music genre..

Now im one happy owner of MC402, yay!
Now im one happy owner of MC402, yay!

Congrats Nicholas. The space is larger but you sit close to the speakers. You said 7-8 feet? Let us know how it works out.

Cheers and Happy Listening
Hi CT0517,

Yup my sofa is about 7-8 feet away from the speaker, behind my sofa is actually the dining area and open kitchen area. Compared to the previous setup using krell 400xi, the speakers are not bass shy anymore. The bass now goes deep and tight (not as fast/accurate as the krell), and the sound is much fuller. Instrument separation is at another whole level, and the soundstage is wide and you can feel the 'depth'.

I find that the larger area actually provides more space for the speaker to sing (note that I did not so any sort of room treatment, but just let it sings freely in my living room). Overall im really happy with the MC402 pairing up with the olympica II.

I also did some trial between the 4ohm vs 8ohm output from the mc402, and i like the 8ohm more (olympicaII is rated at 4ohm). I find the sound from 8ohm is more dynamic and accurate, while the 4ohm is slightly better at midrange (smoother & sweeter)..

Once again thanks everyone who contributed their feedback!

Nicholas, Did you know that McIntosh was responsible for the amplification at WOODSTOCK (now if the sound was bad, all those people would have ). You made the right choice. McIntosh makes some of the best amplifiers on the planet, in all respects ie...Beauty and quickness of sound, reliability, ruggedness, and build quality with stunning looks. The reason you like the MAC is that at high volume levels it dosent drive you out of the room! All the while still providing the emotion and presence of the musical event. Fatigue is a non factor when listening. These are hallmarks of McIntosh amplifiers, and they have only improved their design over the last 60 years in business. McIntosh makes a lot of products, but their amplifiers (2 channel) tubed and solid state are what the companys foundation is built on. Great choice!

Matt M                                    



Congrats on your purchases!  I've lusted after McIntosh equipment for decades.  This year I moved my music audio system down from our 13x24 living room, to our 24x26 "man cave", as I became smitten with a pair of larger, floor standing speakers.  I found a C50/MC452 combination for sale on Audiogon and drove a few hundred miles one Saturday to retrieve the pair from the seller.  When I am really cranking it, the needles on the MC452 dance around 4.5 watts.  I really like the smooth, musical sound of the McIntosh equipment, I have found slight amounts of fatigue listening to other brands.

Enjoy your purchases!