Best sounding low power (under 80watts) Class AB amp?

@hi2alex2 -- what are you talking about? The Vidar has left and right RCA line inputs -- the same as my Aegir which I'm listening to right now.  The only reason there is also a XLR input is if you wish to use the amp in mono mode for higher power output, and then you'd need two Vidars for stereo operation. 

Simaudio 330A. 

Topping LA90 is what I am using now. I picked this with the same criteria as you are looking for. Low weight, Class A/B under 80 watts, runs only slightly warm. It has beat out the Benchmark AHB2 as the lowest Sinad measurements. I've sold off the heavy and hot Pass Labs X250.5, Classe Monos and have my 150 pound Enlightened Audio Designs PM 2000 for sale. It can be used as a three input integrated, high/low bias and also mono. I have tried it in mono and I didn't hear any reason to go that route so, the value proposition is high for this amp. 

@mlsstl @ditusa  I could be mistaken but what I see is chassis mounted 'binding posts' not RCAs. The RCAs on the Aegir/Aegir look to be circuit board mounted in plastic cups which are screwed/supported by the chassis. It's not the same.

@rrboogie You replaced your X250.5 with a Topping LA90? Are you an EE by chance?