Most transparent power amp

Benchmark AHB2 is the most transparent I've heard.  It supposedly has the lowest SNR/noise floor available.

I highly recommend the Bryston cubed series, choose the size that fits your setup and you can't beat the warrenty.

Hi Lawence,
There are some really good companies listed. Here are a few more suggestions that you may want to check out.

Rogue Audio - Tube - great solid build, best value for the money $$
Ypsilon Electronics - Tube - fantastic design, it will cost you $$$
Tidal - Solid State - "The Rolls Royce of High End Audio" $$$$$

Add Van Alstine. 

Hands down ultimate to date is the Acoustat DD Servo OTL. It happens to be tube but could just as well be ss. Eliminating the interface is the point. That's the game changer.