Pass Labs XA25 or 30.8? RCA/XLR vs noise floor and slew rate

[Exophile]

I am looking into breaking up my integrated amp into all separates. So far, the Pass Labs XA25 and XA30.8 are the top contenders. I will be driving PearlAcoustics Sibelius SG 8 Ohm speakers in a relatively small room (36 m2 / 350 sqft) and not at ear-shattering levels, so the XA25 should be fine. There seems to be a trade-off between RCA connectors on the XA25 vs. XLR connectors on the XA30.8 with common mode rejection. However, the XA25 has a better noise floor and better slew rate compared to the XA30.8. I am leaning more towards the XA25, particularly for the slew rate. Any thoughts?

Second, for preamp, my top contender is the PrimaLuna EVO 300 with RCA in/out, or the EVO 400 with XLR in/out. if I go with the XA25 with RCA inputs, I don't need a preamp with XLR out. I only have one XLR capable source (HoloAudio May DAC L2), so wonder whether that would justify splurging for the EVO 400. I think rather not, but welcome some insights/experiences/opinions.

Thanks!

[hifinutt]

How did you get on ? The sibelius speaker seems to get a lot of praise and would love to hear one

[Exophile]

Hi Phil,

I got the PrimaLuna EVO 300 Pre in, waiting for the Pass labs XA25 to be built. Maybe another month or so. I selected the 300 over the 400 as the internal design is not fully balanced. I don't see the point of having fancy sockets on the back without getting any benefit of balanced design. I selected the XA-25 as the I don't need more power, and Harley with Sibelius noted that several of his customers are happily using the PrimaLuna XA-25 combo. Harley's customer care is the best I have had with any hifi company. Absolutely stellar.

Re the Sibelius, I can compare them to my previous B&W CM6 S2 speakers. I could hook them up to my current integrated (Rotel RA 1572, before I got the PL300 in) and A/B comparison test them with quick switches of the A/B speaker selector, using identical cables. Top detail is better in the Sibelius, no lack of bottom bass extension, though my REL T9i gives a bit more lower end, as is to be expected. The biggest difference is in the lower mids, which are bloated in the B&W, and rather lean in the Sibelius. Listening to baroque chamber music where I know the instruments very well, the Sibelius brings them out spot on, also rendering the room (stone building) accurately, while the B&W makes them sound more like in a padded room: small and muffled. In sudden fff-pp transition, I finally "heard the room". I always thought that was audiophile nonsense, but now know what it means.

I also listen to darkwave, coldwave, EBM, etc. There the sometimes tiring aspect of the synth percussion evaporated with the Sibelius. If you like gut punching, window rattling bass, you will be disappointed, but if you like clean bass with finesse, you will be pleased. I am still going back and forth re the REL. The sub adds bass extension, but also muddies the crisp sound of the Sibelius. I switch the REL on depending on mood.

One "problem" of the Sibelius is the relentless accuracy and detail. A small hiss on in a presto violin piece comes through equally prominently as the finest pp-p-pp messa di voce. I also got the speaker stands, but could not hear a difference. The PearlAcoustics speaker cables with AWG 5-6 compared to AWG 14 of my previous Cardas 101, may give a tad more bass, but it may also be confirmation bias.

The PL pre is a good pre-upgrade to the pre-stage in the integrated. More detail, better soundstage, but also more musical. Often detail is the opposite of musical, but here it is both. I know that I am still using the Pre-section in the integrated, but it still sounds better going first through the tube 300 pre. Definitely looking forward to the Pass XA-25. The improvements by the Sibelius already on rather entry-level electronics suggest that the difference with better pre and power amp will be more pronounced. I won't be able to do the test, as I traded in the B&W already. But I have noticed that with headphones and DACs.

Let me know if you have any questions.

[hifinutt]

Thanks so much for that very detailed reply. I did try and demo a int 25 with no success. However using a bel canto pre 3 with some pass f4 clones which sounds glorious. I have a feeling the sibelius would love that combo too .

Hope the xa 25 arrives soon

[Exophile]

I think there is a Sibelius "ambassador" in London, so within reasonable travel distance from the midlands. Not sure how auditioning would work, particularly in covid times, but if you are interested, send an email to Harley. I bought them unheard, just liked the concept of single driver - no crossover, and the reviews sounded right with what I was looking for. No regrets here!

I forgot to mention, I was also concerned whether the relatively small drivers would be able to play loud. I have a fairly small listening room, about 18x18' set up diagonally, with speakers about 6-8' from ears, so midfield. I turned up the amp till it was getting definitely too loud (hearing damage level) and I could not see the driver cones move. There is a video on YouTube that shows the driver cones moving. That must be crazy sound level. So even with larger living rooms, I would not be concerned about filling the room with sound from the Sibelius.

[Macca]

with that budget and those speakers I'd go for a Radford STA15 with a passive stepped attenuator pre-amp. But the X25 does look like a good choice too.

[hifinutt]

I think there is a Sibelius "ambassador" in London, so within reasonable travel distance from the midlands. Not sure how auditioning would work, particularly in covid times, but if you are interested, send an email to Harley. I bought them unheard, just liked the concept of single driver - no crossover, and the reviews sounded right with what I was looking for. No regrets here!

I forgot to mention, I was also concerned whether the relatively small drivers would be able to play loud. I have a fairly small listening room, about 18x18' set up diagonally, with speakers about 6-8' from ears, so midfield. I turned up the amp till it was getting definitely too loud (hearing damage level) and I could not see the driver cones move. There is a video on YouTube that shows the driver cones moving. That must be crazy sound level. So even with larger living rooms, I would not be concerned about filling the room with sound from the Sibelius.

thanks , yes i believe its art + sound in london

https://www.facebook.com/art.n.sound.uk/

already got too many speakers but certainly would like to hear sibelius at some point . the fugalhorn xl was here for a while and really made an impression

[Exophile]

Re amp choice, had not seen/heard of Radford. Me being in California is a factor, and Pass is in CA as well. I was considering a PrimaLuna pre-power combo, but the output impedence/damping factor of the power amp is horrible (DF of 1-2!). That seems to be the case with many valve power amps; not sure about the Radford. Could not find any info with quick googling, which generally is not a good sign. Still waiting for the XA25 ...

[Exophile]

Art & Sound sounds about right. They had a nice review of the XA25 on YouTube.
I don't have multiples of any gear. If one is better, then the other one goes. I think I have one exception with phono cartridge. The cleaning folks cleaned off the stylus&cantilever of my SoundSmith cartridge (ouch!), and repair takes 8-14 weeks. Did not want to be without a TT for that long, so bought a tie-over Ortofon 2M black. Will re-install the Zephyr MIMC* once it comes back.

[Macca]

Re amp choice, had not seen/heard of Radford. Me being in California is a factor, and Pass is in CA as well. I was considering a PrimaLuna pre-power combo, but the output impedence/damping factor of the power amp is horrible (DF of 1-2!). That seems to be the case with many valve power amps; not sure about the Radford. Could not find any info with quick googling, which generally is not a good sign. Still waiting for the XA25 ...

Sorry didn't realise you were over the pond. Forget Radford then.