Pass Labs x250.8 vs tube amps

@chungjh
I left my X250.8 on. This afternoon, it started sounding good around 2 hr mark. Less sibilance and harshness.

Similar situation with my prior dual-mono MOSFET SS amps I ran for 20+ years. Mine did still keep sounding better at hour 4, and more dimensional at hour 8 when they are on all day long. Similar to Pass .5 and .8 amps. There are several threads on this, owners debating this.

Tested and made notes today on my own tube mono amps with big transformers. 60 minutes was listenable, but hour 2 became plush and 3-dimensional. I cannot listen to them until at least 1hr warm-up. Kinda reconfirming again its just so much better at hour 2 with my tube amps too. Once it hits that bias set point, becomes very musical, enjoyable.

I leave my Pass amp on all the time now and still warm up for a couple of hours to sound GREAT. But, I still hear sibilance in Diana Krall's tracks and some others. As I get older, this sibilance thing bothers me more and more. At my volume of playing, I am still deep in Class A, and yet still sibilance. Does this mean I have to bite the bullet and go for a high end tube amp? This review on Conrad Johnson's ART150 sounds good: inner detail but smooth. Of course, it is close to $20,000. Do you think the reviewer is exaggerating and do you think CJ is worth the price?

Hi @chungjh`
"worth the price" is in the eyes and ears of the beholder and a person’s wallet I’d guess. CJ has a huge following just like Pass or Cary or Audio Note, etc. I’ve not heard the new Art150 or Art300 myself. I have been reading comparisons as I run two mono amps with KT150 tubes myself - wondering how and why the Art150 costs $15,000 more. Knowing CJ through colleagues, I’m sure it sounds``wonderful.  I’d have to hear that amp in my own system on my speakers before I’d conclude its worth it.

A buddy owns that $20k GAT preamp by CJ. He compared it to my same $4.5k tube preamp with upgraded caps in it, and reported he’s selling the GAT preamp pocketing the difference. Don’t forget that Art150 amp will need a worthy preamp to go along with it. The cost adds up quick.  I was at the same point you are now about "ears" and led myself back to tube amps, different interconnect cables, a tube DAC, and even changing coupling caps to smooth things out even more. There may be some things to try with your own 260.8 before going all tubes.

My own KT150 based amps were still a tad bright to me until I installed good NOS small input/signal tubes and changed coupling caps in them.  Upgrading a standard build tube amplifier with standard upgrades used can be amazing when done by a good tech who knows how to improve a line. A good friend just had two different CJ" amps upgraded lately and likes the difference quite a bit.  Everything I’ve heard myself at Deetes with SoundLab speakers has always been pleasant, yet it’s always been tube preamps and tube amps powering them. You could also try a proper tube preamp with your 260.8 in an effort to keep it. I’ve had email conversations myself with Nelson on this topic, he has many customers running tube based preamps with his XA and X amps. Feel free to send me a PM.  

Yes, I am running BAT rex2 tube preamp with my Pass Labs. It sounds better with it than without it when I go direct from Lumin X1 streamer/dac which has outstanding LEEDH volume control. One option is to get rid of rex2/Pass and go directly from Lumin X1 to a tube amp, to get the tubes smoothness. If I do this, I can go for a much more expensive tube amp.

Hi there.  I had the ARC Reference 10 pre and Ayre MX-R monos.  They turned my audio room (16' x 18') into a hot yoga facility after about 3 hours of play.  Also, I wasn't that pleased with the sound after a visit to the Munich Hi-End Show and hearing what other systems at the same or slightly less price were delivering.  When I returned I continued my research and testing.  I landed on the Octave Jubilee (a hybrid with a solid state power supply) and the Octave MRE 220 w/ the "Super Black Boxes", which are external capacitance power devices (one per mono amp).  They are leagues above my old components in their build quality and sonic performance across all parameters of measurement and evaluation.  To single out just a few qualities: incredible inner detail and nuance - check; accuracy in tone and musical pace - check; a vastly bigger, deeper and more defined soundstage - check; and, a much fuller, deeper and more articulate bass - check again.

But moving to your concerns.  The components need no more than an hour to achieve full potential and the tube pre and tube monos together give off far less heat than just my ARC Reference 10 did (a two box unit with a tube power supply).  Tons of power from the MRE 220 amps with and without the SBBs. 

There is so much great gear across the pond providing far better performance and value.  You only need to visit a handful of European countries to quickly appreciate how much more they are into music than Canada and America.  They've had a head start and it shows.

Ray