Hello; I have an Art Audio Jota, that I purchased used on the net. IMHO, it is THE finest amp I have heard/owned, in over 20 yrs. of this wacky hobby!. I understand the Diavalo is extremely GOOD also. Upon recieving this amp, I called Art Audio's Joe Fratus. He took the serial # of my unit, proceded to give me a history of the amp, listed me as the person in which the transferable warranty is now under,given me tube recomendations, and in short...talked audio with me, like we were old next-door neighbors. I have a claim with FedEx pending on tube damages, in the shipping of this Amp, and Joe has been very helpful with providing me with documentation, replacement box, etc(even though he had nothing to do with MY sale).
In short, few Companies that I have dealt with, come close to the superior customer service offered by Joe Fratus and Art Audio.
I have not directly compared Art Audio Amps with Sonic Frontiers, but I will stick my neck out and say: trade your Cardas Ref XLRS in for RCA's and go with Art Audio, I do not think you will regret it.
In short, few Companies that I have dealt with, come close to the superior customer service offered by Joe Fratus and Art Audio.
I have not directly compared Art Audio Amps with Sonic Frontiers, but I will stick my neck out and say: trade your Cardas Ref XLRS in for RCA's and go with Art Audio, I do not think you will regret it.