Pass Then vs. Pass Now

@jjss49 Thanks !  As you've said, Nelsons' First-Watt "kitchen-table" amplifiers were designed for sounding terrific from the first-watt in mind.  The reliability also of the Pass-Labs and First-Watt electronics is well-known.  Nelson is also one designer who is very willing to share design information and I've e-mailed him questions about my amps on several occasions.  He's always gotten back to me and rather quickly, considering he must be a pretty busy man.  I love the minimalist approach to the First-Watt series and the sound of very few active components "singing" through a fairly efficient speaker can be captivating.  It was that way with the SIT-2 and my Volti Vittora's.and even my Living-Voice OBX-RW's. The Vittora's are long-gone as there was no room for them in our retirement cottages' small listening space, however the 106-db single driver speakers are coming soon ! Happy listening !

I’ve heard the first watt, it’s an amazing amp, the x25 is on onother league, musically dynamic.

Great discussion everyone. Really appreciate all the feedback and lively back and forth. 

@liquidsound you raise a great question. Being that I live in an apartment I can't really play too loudly. In fact one of the reasons I am looking to upgrade aside from a general improvement is that I find I need to turn the Sphinx up considerably before there is any weight and dynamics to the music so I am hoping to achieve a fuller sound at lower volumes.

@audphile1 I am glad you brought up the Audio Research LS-25 and Ref1 preamps in combo with the pass amp. Although I am not ready to purchase a new pre yet, I have started to look around and aside from the obvious pairing with an XP-12 I was gravitating towards the AR Ref 3. I also read some really thought provoking reviews of Shindo Labs pre amps but those might be just out of my reach price-wise and difficult to find as well. 

@twoleftears

in my 17x20 room, i have a listening triangle roughly 11 ft equilateral, i don’t listen real loud, rarely exceed mid 80’s db peak loudness

in that context, with my mon 40’s all pass amps drove the speakers very satisfying for my listening... bass control is also excellent... i had an f6 for a time, felt that one was maybe just a touch loose gripping the woofers... my f5 is modded with extra power supply capacity (bear in mind the f5/f6 are push pull amps, not single ended as most lower powered fw amps are) so that one does fine too, xa25 xa30.5 and up all sound effortless

parenthetically, i would say my favorite for driving the mon 40’s is the linear tube audio zotl40 reference, with a pair of rel subs augmenting the deep bass crossed over very low.... that is a hella sweet combo... clarity, purity, vast spaciousness, excellent impact and of course, the midrange magic in spades...

hope that helps

FYI. I used to own a Pass preamp and amp… and found the Audio Research preamp and Pass amp to be the preferable combination. The ARC has a better midrange bloom… more natural and fleshed out. It really is ARC’s thing… preamps. 

@theschwartz yup ARC with Pass is excellent, you can’t go wrong. Take it one step at a time. Upgrade as time and budget allows you to do so but getting the amp first is the right move. 

@theschwartz  Great discussion everyone. Really appreciate all the feedback and lively back and forth. 

@liquidsound you raise a great question. Being that I live in an apartment I can't really play too loudly. In fact one of the reasons I am looking to upgrade aside from a general improvement is that I find I need to turn the Sphinx up considerably before there is any weight and dynamics to the music so I am hoping to achieve a fuller sound at lower volumes.

While I can play music loudly, most of my musical enjoyment is at moderate volumes and if your speakers have challenges coming "alive" until they're played at higher volumes, perhaps it could be them, or possibly the equipment.  If you really like the sound of your speakers played at lower to moderate volumes, finding an amplifier that can do that could be the best thing.  If you can borrow an audiophile friends' solid-state amp to try and see if the weight and dynamics are better at your ;lower listening volumes, the direction may be clearer as to where to go with amplification.  What I have found with the Pass-Labs and First-Watt amps is that Nelson Pass has designed them with power supplies that are superb and when I have listened to them at lower volumes, the dynamics and "weight" of the music seems proportional to listening at higher volumes.  It gets back to I believe his design philosophy of if the first-watt doesn't sound good, how can the rest sound good ?  There are good reasons for my sticking with First-Watt amplification and I also have a superb 300-B tube amplifier (BorderPatrol S20) that rivals the First-Watt SIT-2.at low and moderate volumes.  However, the differences really come to light more with efficient speakers.  I can speak of this in more detail from my experiences in another post.  

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.