Anyone heard Resolution Audio Cantata C-50 amp ?

The C-50 is the new more powerful version of the OPUS 21 s30 amp.

Reviews say that it is very fast and musical (DNM like) but dont state if the sound is on the warm or cold side.

I am looking for a fast and warm SS amp with zero or low negative feedback for 6 Ohm average / 4 Ohm minimum / 89dB accuton ceramic driver based speakers.

I have heard the C-50 and it is fast and musical as you have read.
Please message me for more details.
I've owned the GNSC Reference modded RA Opus 21 and s30 for several years. I recently purchased the RA Cantata Music center. I've heard and demoed the C-50 extensively. I did not purchase the C-50 because it did not have the second set of speaker connections that the s30 had.

I would say that the C-50 is slightly on the warm side of neutrality. It is definitely not a overly warm/lush sounding amplifier. It is very open and and fast and very musical. I heard it drive a pair of loudspeakers that were 85 db efficient with no problem. However, I wouldn't think that 50 watts with your loudspeakers is going to blow the roof off your house :) If possible, I would try and demo if you can. Good luck.

I have an Opus 21 stack, consisting of the Opus 21 CD player, power supply, s30 integrated and XS ("Extra Sources"). Mine, too, was modified by Great Northern Sound. I understand that the C-50 is based on the s30, which had lots of good low bass, provided that you don't mind living within the power limitations of a 30 watt amp. I listened with my Verity Parsifal Ovations, and they sounded fine at moderate volumes; I don't listen too loud under any circumstances. I use my s30 now with Spendor LS3/5a's in a very small room and find that highly satisfactory, all of the volume limitations above restated here for this outfit.

I understand that the C-50 has a lot the same sound as the s30 but has a bit better resolution and twice the power. Since Steve Huntley is representing Resolution Audio now and has a ton of experience with both the s30 and C-50, why don't you contact him at Great Northern Sound Company (651.351.5355) to get his input. He is not a dealer anymore and would refer you to a dealer near you if you want to purchase a C-50 but he is a straight shooter and his opinion is likely to help you.