Amps for B&W 805 Diamond: Rogue Audio or Krell, Pass labs, ML, Accuphase

@truongv0ky it’s pretty common for any component to take some time to start sounding its best after it’s on and out of standby. It will sound just fine when it’s cold but will get even better after about an hour is what I’m saying. It isn’t proprietary to Pass Labs gear and I wouldn’t classify this as a problem. 

@truongv0ky I ran B&W N803 with Pass XA250.5 and Audio Research LS-25 preamp. Great combo. The XA series would work well with the 805s.
I think the sound you’re looking for you’ll find with Pass XA-30.8. 
I had Rogue separates (ST-100 and RP-5) and while very good the Rogue stuff tends to lean slightly towards dry sound in my opinion. 
Also, your Chord Qutest will be a good match with Pass Labs gear.
The Qutest has great tone and it won’t be masked or veiled by the Pass amp.

Have to disagree with @soix here. 
The Pass Labs XA series is more refined than the X series. Let’s not confuse refined treble with softness. I’ve owned both X and XA. There is no softness in the treble region with the XA30.8. It breathes life, details and tons of air into the music. The midrange on the XA is absolutely clear with zero glare. Bass is big, deep and plush. A welcome trait for the 805D. 
At the end of the day, you can’t go wrong with either the X or XA series. Pass amps kick butt with B&Ws. 
McIntosh newest stuff should work well too. Their new integrated amps are very good. 

@soix 👍 

Something else to add…

One downside with Pass labs gear, if you can consider it so, is the fact that it takes about an hour minimum for their components to warm up and perform at their peak. It isn’t exclusive to pass however in the case of XA with pure Class A operation you’re looking at 380w power consumption at idle. I never measured how much the XA30.8 amp actually pulls from the wall during normal listening but I’m pretty sure it isn’t shy. If that’s a concern then opt for Class A/B X series. Slightly more efficient. As far as heat, the XA gets warm but won’t be a space heater. It’s more than tolerable. Hope this additional information helps as well.