Not hardly, I am very fussy about audio (more than most) and much more than watt meter.
What is the surprise? Hybrid rigs like 520 have a tube driver and tube finals which have a wider dynamic range than most SS devices and therefore tend to do better with audio/modulated RF. While tubes are relatively fragile, bulky and make heat they still do a excellent job with audio reproduction that many SS devices still struggle to match. Some hard core audiophiles still use tube amps.