That’s interesting and in line with my thinking. I’m yet to be convinced of DR in all applications. Yes it made a difference on the NAP300, but that doesn’t automatically mean all DR will be better, at least in my head and half the fun for me is trying things and finding out for myself, but it’s always good to get other people’s take on it. I do realise that the larger part of this forum seem to prefer DR, with the odd exception, 555nonDR with nDac being a notable one.
Oh and it’d definitely be second-hand (I definitely couldn’t justify £7500 on a new one) and both the 555non-DR and XPSDR seem to be around £2500-3000, it’s just that there are far less 555s.
I did the same too, l bought a 555 ps non DR and it’s absolutely caned the XPS Dr to my NDX2, lm now tempted to know if an even further improvement can be made by exchanging the 555 ps for a 555 pd dr, the trouble is demo units are in short supply and it could prove costly if l just presume a DR unit would be better
As far as I know, all 250 are regulated. See this thread
I know the recommended interval is now 12-15 years, but my main point was that you can’t really rely on regulated amps working well longer than that, and in particular can’t rely on them failing gracefully when they eventually do
