fwiw, i listen to modified 502b with rolled tubes thru my kestral 2's and the guy that says the sound is mid or low fi is off his rocker... i am not an expert in tubes per se but i can tell the difference between very good musical sound reproduction and mid fi! many tube amp owners say modifying makes a big difference and maybe this is the case here as well. nonetheless, paying $2K more for so called high end quality with half the watts sounds like money down the rathole unless you have extremely efficient speakers and or a big ego and 24K golden ears! seems to me a lot of pseudo-audiophiles think price and quality define musical sound reproduction. i'd rather ride in an older caddy than a new bmw on a cross country road trip!