How is the Pass Labs X150.5 at low volume?

Pass Labs amps are exceptional having owned a number of them for forty years. But I would not call the x series warm… they are not cold or analytical. I have nothing but praise for them. if fed a warm signal you will get warm output. The XA series are a bit warmer.

I had gotten interrupted in my post and due to the time limit could not edit or complete it.

I had failed to address the midrange directly. The ARC amp has midrange bloom where instead of a good solid rendition of colors with the Pass the whole spectrum is laid out in rich warm colors. This in part is why the Pass amp has so much slam… it is very fast and without such a well fleshed out midrange highlights the fast rise in bass and really slaps you, as if nothing else was there. Voices are rich and pure on the ARC.

Back to perspective. These are two great series of amps the Pass x series and ARC tube. The Pass XA series is definitely closer to the tube sound, but not all the way there. There are people attracted to easily hearing the drummers foot slapping the pedal or highlight the venue and mastering techniques, or need massive power and the solid state amps like the Pass x series are an outstanding choice. But for great rhythm and pace… one of the most important drivers of emotional connection and musicality tube amps / components tend to get this better.

@chorus

i can characterize the difference between the Pass x350 and ARC Ref 160s. The difference is profound. Both have house sounds of their respective companies.

The most obvious difference is in slam and detail. The Pass amp has notably more slam and the details are more up front and highlighted. Before you have a real positive reaction to that… it is not a complement. The Audio Research has much better bass… bass doesn’t sound as it if of a narrow frequency… but a full rich wide band rendition of bass… sounding much more realistic like would be heard in and acoustic concert. It hits your chest as opposed to being a quick slap. The treble has a very different character as well, the details are all there if you listen, but they don’t unnaturally stick out.. the brass of cymbals more like brass and less undifferentiated treble. If you go to an acoustic concert… you hear the same thing. But then put on some loud electronic music like Yelo and the bass and detail within the bass and the layer out wide frequency response is incredible with the Audio Research tube amp. I had planned on switching my Pass x350 back and forth with the ARC… but never did… there was no reason. Later I found out the ARC amp I was auditioning was not broken in… it sounded better and better over time. Overall musicality was far far better with the ARC tube amp… it sucks you into the music quickly… the Pass sucks you in to listen to all the details and contrasts of sounds. The Pass exceeds at high contrast (using a visual comparison), the ARC a higher resolution low contrast.
They are both very quiet amps. The Pass XA series sound more like the ARC… but not nearly as far along the continuum as the ARC. 

Sounds like you are at a crossroads. I have owned Pass amps for 40 years… typically of higher wattage… but they have the same character. I have also own Audio Research equipment Preamp / Phonostage. I cannot address your question directly… but my ARC amp sounds better at low volume than my Pass amp… but it would be a real stretch to have this be applicable to your situation.

I hold Pass in really high regard… but about ten years ago I began moving closer to all ARC gear. The outcome has been incredible. While my amp is of lower power my system is sooo much more musical! When I got to all ARC my system took on a real musicality my system never had. BTW, I am using a ARC Ref CD9se for DAC… I compared with a $22K Berkeley Alpha and I thought the ARC sounded better. Anyway after forty five years of solid state I moved to a ARC tube amp and will definitely not be moving back. My system sounds great at low volumes.


You can see my system by clicking on my ID… noticed a number of similarities.