Pass Then vs. Pass Now

My experience with Rogue RP-1, RP-5 and ST-100 was similar - the sound would open up at higher listening levels. At lower volume it sounded a bit dry, less vibrant, less detailed and more restricted.
With Pass gear you get way more of what’s on the recording at lower volumes. Going up in volume gets you bigger images and more expansive soundstage.
My preference for the sound is to be close to optimal at around 80db measured in a listening chair. If you get extreme resolution at much lower levels in most situations it means at higher volumes you just won’t last long before the fatigue sets in and you want to shut it all down. That’s just the nature of the beast. So be careful there…try to strike that balance.

Thanks! I am leaning towards the XA30.8 for many of the reasons stated here. I think I needed to hear someone say that it is in another league above the Rogue sound that I have been listening to (and enjoying - that Sphinx punches way above its class). 
 

I hate to burst your bubble, but the Sphinx doesn’t come anywhere near punching well above its class IME. My $250 Yamaha A-S500 integrated outclassed a Sphinx V2 by every metric, as has every other integrated amp I’ve owned, of which there are many. 
 

To say my Pass XA25 and Bel Canto preamp are in another league would be the understatement of the decade. An apt analogy would be comparing a VW Beetle (the Rogue) to a 911 Turbo. 

Update, pulled the trigger. An XA30.8 is on the way to me. Looking forward to testing it against my expectations. Will circle back to report on my impressions after I spend some quality time with it. Thanks again to everyone for chiming in with advice! 

Congrats! Keep us posted.