BUYERS BEWARE...I’ve had a 502P for over four years and it’s been nothing but trouble…sapping me of time by compelling me to spend hours listening to it instead of doing something to help those less fortunate than myself (and some more fortunate than myself), and staring at the stupid tube glow…nobody needs this crap. I thought, "I’ll get a Jolida and go for the cheap factory upgrades and stop thinking about it" but no…tube rolling, endless posts about how cool the Jolida people are to talk to, how rare reviews are, basically zero advertising, how my 502P is too inexpensive for audio geek credibility, how "audio salon" owners make me listen to Rogers, VTL, and ARC stuff that doesn’t sound better…insane…it's not easy being a Jolida owner. Not easy at all. A recent post noted that an ARC tech said KT150s could kill a 6550 specific ARC amp’s transformer…over a year ago I stuck 150s in my stupid 502 (after 3 years of KT120s) and what happens? NOTHING…it just sounds better…no transformer heat issues, no hum, no problems at all…the 50 pound amp just sits there with the tubes glowing away like it just doesn’t care…at least with the ARC thing you can worry about something…nothing…man...