The standard-edition Wavelength Audio Cardinal is priced at a mere $5250/pair. Each monoblock uses a 5AR4 to rectify the high voltage for the plate supply, a 6SL7 in the gain/driver, and a single 300B output tube. Brown-bottomed Golden Dragon 300Bs are standard. Various tube choices are available from the manufacturer, including original Mullard 5AR4s. The power is rated at 7+ watts per channel (Wpc).
Let's see...$5250/pair divided by two, divided by 7. That's $350 per watt per channel. We're talking…