I own one of these, it's now my secondary amp. Very good piece of kit. But if I was going to buy it and use it as my main amp for critical listening, I'd have it recapped, have the regulators replaced, and have it rebiased. It's old enough to need that. I believe MF will do that for you - they have a program of bringing old units up to spec "like new", but if not, there are plenty of reputable places that can do it. It will greatly improve the performance of the amp and improve the sound. Will be like having a new X-150 for much less.