I think in both cases you will prefer the Class A versions of each manufacturer's lineup. Which of the A/B amps you are familiar with do you prefer? I suspect you would also end up liking the same manufacturer's Class A design over the other. I also suspect that you will love whichever one them you choose - both among the best SS amps available. The Pass XA-30.5 is the best SS amp I have ever heard - but I don't need much current or watts for my speakers.