Amps for Avalon Osiris CAT JL3, Boulder 2060, Dart

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.

Brian

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.
Jeff

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.