Amps for Avalon Osiris CAT JL3, Boulder 2060, Dart

I recently purchased Avalon Osiris and am considering what amps to use with them. I purchased a pair of Levinson 436's as a stop gap just to have an amp that could drive them while I saved for a better amp. I am using Stealth cables throughout (Indra IC's, Dream PC's and Dream SC's).
My preamp is CAT Ultimate MK2 (line only) with NOS Amperex PQ's. My DAC is Audiologic 24MXL and CEC TL2 transport. I am open to other amps than the three listed above but am leaning toard solid state or hybrid. I am trying to avoid space heaters. Some other amp considerations are VTL Sigfreid, Tenor 300's ...
WOW. Eidolon owner considering Ayre who happens to be coming out with a new monoblock. MBL?
"Pos",great stuff in store for you.How about those Amperex's?My best pal's phonostage had them, and superb!!
In response to your question,I have heard the Osiris,and own Ascent Mk -2's.I live in the N.Y. metro area,and have made it my business to become familiar with the vast majority of superb products that are currently available.
The Osiris was/is a SUPER PRODUCT!As you know.You do have to be very careful about cable/component matching to get the most from it.It is an extremely revealing speaker,and is easily competitive with the best of today's stock.
The important thing about amp compatibility is to think "tonal color" as opposed to high volume capability.This can become tricky as there are so many choices,and many people are impressed by dynamics soley,which you will surely get,with the right amp.I have gone through the tube/solid state wars,over my 38 years in this hobby.Love tubes!Hate sitting in my own sweat,in my dedicated audio room,which is a closed off environment!!I guess one cannot have it all.
The finest tube systems(low power)are superb,and have a stunning tonal palette.Solid state,in the past,has not been great here,yet the current crop of "Elite" solid state is closing the door here,Big Time!!!
I have run my superb Ascents(with REL STENTOR sub,coming in at 26 hz)with superb tubed and solid state.I have chosen solid state because the best units are superb,today,and I didn't appreciate sitting in my bathing suit,in December.All while the outside temp was about 25 degrees.
This was a tough choice,but my current highly modded(customized) Rowland,two chassis model 8t,completely fills MY bill.
OK,as to you,and this is only an opinion,the choices are many,yet the way you drive the speaker is important.Will you Bi-amp?Or one amp?I assume you will tri-wire,if only one amp.Room size is important in such a decision.
The Osiris is one of a handful of the "absolute cost no object" best designs made.In musical truth!Not home theater,as many of todays designs are voiced for.
OK,here are some of my own choices,with the vast majority being heard,by me.Actually all,but the Boulder.
The Boulder is a fine choice,and a class A/B design,which will not run hot.It has a fine reputation,but it is VERY heavy,and this weight factor should be considered in a decision,as you may(God forbid) have to have it serviced or modified,and too heavy "sucks"!
My Rowland(before I had Jeff modify it)was 85 lbs in one chassis,and 165 in the other chassis.I've had it updated/modified about four or five times(it's that good,btw)and now that my son is in medical internship,there is nobody "buff" enough to be of help.BAD!!Think about it!
Other alternatives are the current crop of Pass stuff.The .5 series,which really do sound superb.I heard these,and was very surprised as to how good they sounded(remember,my baseline in amps is a superb,full range tube sound,yet preferrably if it can be had in a solid state design,which completely relies on component mating).
The current Rowlands(300 series) are good,but the older 8 and 9 series were probably their best(if modded to his latest Power supplly technology,IMO).Run way cool,too!
The Dartzeel,which I have heard are superb,but may not be such a great match,as to their 100 watt rating.
I have extensively heard the ASR EMitter,which is a super amp,and has the added benifit of a battery driven pre.I have heard it on the incredibly full range NOLA GRANDS.Possibly the most extended high frequencies I have ever experienced,with this fine amp.Though my impressions(remember only my opinion,soley)were that the other high pedigree Solid State designs were darn close,to the ASR,at the very least.
My suspician is that the Gryphon Antilion Signature would be absolutely "world class" on the Osiris'.I take into account the absolute ability to "drive" the speaker load,with the ability to maintain a stunning level of musical texture,and harmonic naturalness.Like the finest low powered tube units.Not easy!!This is a class A design,and may run(will run) fairly hot.
The Tenor Hybrids are a fabulous choice,and sounded superb,when I heard them.The problem is that Tenor went Kaput,which is quite frustrating,as they were really fine products,and(most importantly)were marketed very heavily(especially by the audio press).Sad!!
Well,sorry for my length,but I am very happy for you,and hope you get the most from your wonderful investment!!

Sirspeedy I'm glad you responded to this. We have a lot in common. I lived most of my life in NJ and owned the Ascents for about 15 years before purchasing these. I hated to sell the Ascents but I finally had a room that was too large for them and large enough for the Osiris.
I reinstalled my Manley 350's (running in triode) on the Osiris today. What an IMPROVEMENT! After looking at the Osiris threads on agon concerning the Osiris I was misinformed that they were a difficult load to drive. They are easier to drive than the Ascents (by one db).
The Manleys are driving them with much greater authority than the powewrhouse Levinsons. I have the same consideration as you about the heat generated by tube amps.
I spoke with Lucien at Avalon yesterday about amps for the Osiris and he told me he heard them driven by the Audio Note Ongaku (I think a twenty something watt SET). He recommended Spectral or Rowland if I decided on SS. I heard them at the show in NYC in 96 and to this day it is the best system I ever heard. I am financially drained after the speaker purchase and will wait and listen to as much as I can for at least a year before trying something.
I am trying to put my last system together so I can get off this very expensive merry go round. I know the Spectral gear is remarkable with the MIT cabling on Avalon speakers (96 show). I want to try to go in a different direction for now though. I can't afford to do a whole Spectral system in one shot and since you must do that I'm out for now. Two pair of MIT 850 EVO shotgun speaker cables (one bi-wire and one tri-wire)came with the speaker purchase and evidently they work best with Spectral gear because they were awful with the Levinson amp. I should have kept them just in case I decided to go Spectral down the road. I have already sold the tri-wire pair for a song. I may in the future put two sets of electronics together one Spectral (summertime setup) and a tubed setup for winter. I think part of the reason people are constantly changing gear is that no matter how good the system is their ears crave variety. That is why two superb systems with different sounds may be a good solution. I hear the Dartzeel splits the balance between SS and tubes better than anything else. The Spectral are very liquid sounding for SS and just do layering/soundstage
tricks that are jaw dropping. It sounds like you feel the Antilleon has the best of both worlds. I saw one for 10 grand on agon yesterday. I'm tapped out financially right now but there will be other opportunities. I would also like to hear the ASR Emitter. The CAT amps are an option for my last set of tubed amps. So much to do so little money. I am certain that I have found my last pair of speakers though. I loved my Asscents for 15 years the Osiris should hold me for at least thirty. Thanks for the advice and if you have any other thoughts I'd love to hear them. If you haven't heard the top of the line Stealth wires yet check them out, they are on a different level than anything else I have heard.

Bart,you have a superb sense of what you are about,in an audiophile way!I cannot offer anything that would be useful to you,as you seem to have a good feel for what you want to do.That's a really good thing.
You're comment about "variety" is very astute!I do believe this is true,and may be one reason why so many folks have more than one cartridge/arm,or multi components.
My Ascents are underpinned with REL Stentor sub(dedicated room)coming in very low in freq,and with very little gain.This gives me a superb blend,and one Lucien did not feel would work,but definitely does.It really allows the Ascents to be moved out into the room where they stage incredibly well.I simply cannot find a reason to replace them,based upon my listening tastes,and room size.My system is highly modded,and I am quite satisfied with performance.BTW,I am a fanatic about equipment care,and my speakers look about two weeks old.
You're Osiris is another story,altogether.A really stunning product that is really of heirloom quality.The Avalons of that era were voiced to blend well with the Rowland and Spectral stuff,but I have heard Avalon products(from that pedigree)work well with a variety of amps.The sky is the limit for you.
I was fortunate enough to be invited to Jonathan Skull's home a few years ago.He had just gotten rid of his Ascents,for the wonderful JM Labs Utopias.
He had a HUGE NYC loft,and I asked him "how could you get the Ascents to fill such a space",where the Utopias really opened up,quite well.I mean the room was gargantuan in size,and I did not believe the Ascents could possibly be a good match.His response was that they "liked Power",and he used a 400 wpc Forsell amp on them.According to him,they filled that room,but I simply cannot get around the thought.BTW,how did your Ascents perform in areas of dynamics,volume etc when pushed?
To me,the power thing may be important(my room is 22.5x8x13,and not too large),but the TONAL BALANCE,and HARMONIC PURITY of music is what I look to,in voicing my stuff.The best tube set-ups excel here,but some SS designs are no slouches in this area,as of late.You owe it to yourself to hear the ASR!All SS,and not hot running.Very ergonomically appealing for long term pleasure.
I do wish you the best!
Sirspeedy, this may surprise you but I thought the Ascents got slightly hard sounding when driven very hard. I suspect that the amp was the cause of that not the speakers. I was running the amps in full triode. I have only recently discovered they sound much better running in tetrode and it is too late to know now (the Ascents were sold to a friend)but it probably would have been fine at high spl's if I had run in tetrode. I paid special attention to Johnathan Skulls reviews, I thought his sonic values were similar to mine. Now that you have recommended the ASR, I will make a point of auditioning it. I am trying the Nuforce 9 SE's next week. They have a thirty day money back guarantee so it will cost me nothing if they are not keepers. Check out the review on So now on my shortlist of amps to hear are the CAT JL2 Sig, Dartzeel and ASR Emitter. I'll keep you posted and thanks for the advice. Maybe we can meet at the next NYC home entertainment show (It will probably be next year). Bart
Thanks Bart,best of luck!!
I sold my Radians in order to buy a pair of Ascents Mk2 about one year ago. After that I sold my ss amps (monos) and bought a pair of Fourier OTLs (Pantheres). Quite a few members of the audio community were quite negative because Fourier has a bad reputation. My amps proved to be reliable however because the caps mounted are of Japanese origin instead of those that are from India. Pre amp is still solid state (cello). The sound is very detailed with spectacular dynamics. If a small Ongaku amp can drive these speakers a 200watt OTL has no problems at all I assume. Even digital classical records prove to be listenable now. I hear plenty of bottom end (is there any sub that will mate with an otl?). I think the Osirus could also be a good match for such an otl. I read that even newer Avalons with a more difficult load work well with Atma- Sphere. Does the Osirus also have minimum load of 5.5 ohm? Can anybody describe the difference between a Cat and an otl? Has anybody similar experiences?
Hodelrecords, it's good to hear your Fouriers are doing well. They are good sounding amps, maybe a bit on the dark side. The original power supply high voltage electrolytic caps were a brand called Binda, sourced from India, so it sounds as though the previous owner replaced them, probably a good thing.

I don't have any experience with CAT vs. OTL amps driving speakers like yours, but I am familiar with both driving Sound Lab ESLs. While I probably can't offer specific insight into which would do a better job driving big Avalons, I would generally recommend Atma-Sphere MA-2s as a minimum if you're going the OTL route; it may be only a matter of time before the Fouriers fail when driving loads that dip below 8 ohms. Avalon can give you an idea of the impedance. CAT amps should drive the speakers well; you'll have to audition them side by side with OTLs to see if you give up some transparency for the sake of control.

I too grew up in New York and spent many years living in Northern new Jersey. I have lived in Ca. since 1980. I also have Ascent Mk 2 speakers and they are driven by a Pass 350.5 and there is an REL Stadium II in the right hand corner. I do employ an Audio Research Ref 2 as a preamp and there are a pair of Amperex A Frames as the first amplification stage. I have owned many cominations through my 40+ years and an audio nerd and this is the first time I am not considering an upgrade.
Essentialaudio, thank you for your insigts about the difference in sound between the Cat and an otl like Fourier. I have considered Sound Labs but they proved to be too big for my 4x8 meter European room. Until now I am not worried about the Fouriers, they are over 10 years old now and have always driven unkind loads including Avalon Eidolon's. The Atma-Sphere's I know well are extremely detailed amps but lacked power in the lower regions although this might have ben caused by the speaker used (Voce divine's if I remember them well). The main complaint I have aout the Fouriers is the noise level of the fans. The biggest mistake I have ever made has been the purchase of a pair of Mark Levinson 20.5. These together with ML 25+26 lacked dynamics. The big Cello's I had were in a totally different league but the otl's had a more life like midrange representation. You can't have it all. If my Fouriers fail I will try Atma-Sphere.
Hodelrecords, since you may consider Atma-Sphere amps, I thought I'd chime in. The Atma-Sphere MA-2s have no trouble here driving the bottom end of my Avalon Eidolons. They have proven to be a great combination with excellent control, speed and agility. Of course, I can't comment on how they might work with the Osiris, but the Eidolon's 4 ohm nominal (3.5 ohm minimum) impedance is simply not a problem for the MA-2, a superb combination all around.
Thank you Rushton for the advice, the previous owner of the Fouriers also had Eidolons. The sound had a very fine bloom and great transparency. Ascents do have a flat impedance with 5.5 ohm minimum, hence I concluded they would be a good match. As long as the Fouriers work well I stick to them. I hope they will because MA-2's are very expensive (here). Great review of the Walker turntable!
I also hear to classical lp's only, I spin them on a Platine Verdier + Naim Aro+ Vd Hull Grasshopper IV on a sand filled box. Even some DGG's (Kleibers Beethoven Sy #5) sound breathtaking.
I haven't checked this thread in a while. Hodelrecords,
the Avalon Osiris is pretty flat at 4 ohms with a minimum dip to 3.6. The CAT JL2 will drive any Avalons easily and do the bass very well. They have a OTL or SET like mid and you should give them a listen before you go to Atma-sphere. I think one of the advantages they have over other tubed based amplifiers is the use of 6DJ8, 12AU7 and 12AX7 signal tubes. This gives you a multitude of tuning options. Bart
The CAT JL2 will drive any Avalons easily and do the bass very well. They have a OTL or SET like mid and you should give them a listen before you go to Atma-sphere.
I disagree with the characterization of the midrange, but the CAT's strong suit is the bass. If using CAT for the Osiris, I would recommend the JL3s or JL3 Signatures.
I have had both CAT JL3 Sig and Atma-spere MA-2 ( i belive Rushton now has the pair I owned).
I fully agree with Essentialaudio: the Cat's have fantastic bass but are not up to the std's of the MA-2's in the midrange. They are, in fact, a little lean in the MR.
You always have tradeoffs to make. Cat is closer to ss sound than most tube amps.
There is no getting around the thermal issues of tubes, especially Atmas-speres as they run true class A.
You haven't heard what the CAT JL2/JL3 midrange is capable of if you are using the stock input tubes.