Amps for Avalon Osiris CAT JL3, Boulder 2060, Dart

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.
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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.