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I have a Rhea and love it. With a 0.3mv cartridge you are getting to the point where some Rhea's can become noisy, depending on tube selection and maybe age/version. Perhaps the newer ones are quieter, but my 5 year-old Rhea exhibits a bit of tube rush with very LOMC cartridges. I'm quite happy with it, but if you want absolute black backgrounds, you might prefer the Pass, which is definitely quieter.
With a Shelter 501 @ 0.5mv mine is very quiet, but with my low output Dynavector 20xl, I can definitely hear the preamp on very quiet passages or between tracks.
That said, I think the Rhea provides a richer harmonic structure, and it is certainly my preference. Depends on what you value most.
Hope this helps!
I own the Pass XOno and have heard the Rhea in a different system. But I have never compared the two directly. So, like the OP, I'm interested in how they sound different. I wish Mechans and others who have a preference for the Rhea would explain why they like it over the Pass. Dfhaleycko does provide a helpful opinion with a clear description.
Dhcod, I too feel the instruments being played, and that is with my Xono in my system. I find the XOno to be very transparent and silent. It adds very little to the signal from what I can tell and it has plenty of gain for a cartridge with .3mv output. The XP-15 is supposed to be even better, though I have not heard it.
With respect to the Rhea, there is an impedance compatibility issue that needs to be considered.
You mentioned in your other recent thread having a Bryston BP26 preamp, which has input impedances of 15K balanced and 50K unbalanced.
According to JA's measurements of the Rhea in Stereophile:
The [Rhea's] output impedance was a low 110 ohms at 1kHz from the balanced jacks, this rising inconsequentially to 156 ohms at 20kHz but, more significantly, to 3846 ohms at 20Hz. This rise at low frequencies is due to the limited size of the coupling capacitors and implies that the Rhea must be used with a line stage having an input impedance of at least 30k ohms if the bass is not to sound lightweight. The output impedance from the unbalanced RCA jacks was a high 2k ohms across most of the audioband, but as this rose a relatively small amount at 20Hz, to 3.05k ohms, the preamp's tonal balance will be less affected by the line stage having a lowish input impedance.So using a balanced connection between the Rhea and the BP26 would stand a good chance of perceptibly degrading deep bass response, at least slightly.
On the other hand, while using an unbalanced connection between the two components would avoid that problem, you would be sacrificing the potential advantages of a balanced interface with respect to noise rejection and reduced susceptibility to ground loop issues. And you would be using an unbalanced connection at the output of a component whose internal signal path is differential aside from its input stage, which does not seem ideal.
Thanks Almarg, I think the XP-15 has an output impedance of 300 OHMS the 25 is 150 and as you said the Rhea only 110. Thinking with the combo of a low output cart and a solid state pre, the Pass may be the best choice.
Initially I was all Rhea, but thinking technically rather than emotionally (mmmm tubes) now I leaning towards the Pass. These two new Pass units are also using some,pretty damn nice output devices. Think they are what are making the 15 sound so much better than the older xono.
Almarg's remarks make good sense. I note that the "Signature" version of the Rhea uses coupling caps that are twice the value of those in the non-Signature version. (4uF vs 2uF, respectively.) The larger caps would go some distance to ameliorate the problem noted by the Stereophile tester. That is a worthwhile upgrade and could be done rather cheaply if one knows how to solder and owns a non-Sig Rhea. The output impedance at 20Hz would be halved.
Pass Labs service guy Kent English feels the Xp-15 sounds the same as the XOno.
The XOno and XP-25 separate power supplies do seem to reduce noise levels over most any another phono stage..
Perhaps the XP-25 is in it's own league.
I have the XOno and could not be happier driving XA60.5's into Maggie 3.6's.
I also have the XOno. Someone told me that the XP-25 is basically designed for those who have/need two phono inputs because they have two tables or two arms. It's also for those who like the convenience of front panel dials for easier loading and gain changes. The internal dip switches of the XOno are inconvenient at best. However, there are many more options. I load my Supreme at 84 ohms. That setting is not an option on the XP-25, but it is on the XP-15.
The XP-15 does have the same outrageous number of loading options that the XOno has, and they are even on the back panel so you don't have to remove the top plate for changes.
I don't know how the three compare sonically as I've never had the XP series in my system. It may be time to call Reno HiFi to do a demo for the cost of shipping. It's the only way to know for sure how it sounds in one's system and if it has the right loading settings for your particular cartridge/wiring combination.
I used to own the Xono and it is a great phono.
Differences between xp15 and xp25 was more realistic and musically satisfying in every music cliche, depth, soundstage, extension, focus etc a c.
Most obvious is the sense of urgency or vibrancy when music is played, but never sounding hurried or artificial. A sense of ease and control at the same time.
Only downside is the xpo-25's susceptibility to power supply interference. My cj GAT with its large pose transformer made life difficult with him coming through the speakers. With some component moves and the xp25 PS being as far away from the control unit as the cable is has given me silence.
It has been too long since I had the Xono for meaningful comparison vs xp-15 however from memory that ease of delivery seemed to be there with the Xono.
If I was in your shoes and looking at upgrading your phono worth Pass, the xp-25 would be the only option to consider.
Thanks Downunder. I appreciate your perspective. The XP-25 and XP-30 are certainly on my list for the next two major upgrades to my system. It may be a while though. It's costing more and more to go up to the next level.
I now have the power supplies for both the XOno and XP-20 on the same shelves as the control units and I've been thinking about moving them to the bottom shelf and having both control units on the top shelf. If I hear a difference, I'll report back.
Well, I did move the power supplies down so both are on the middle shelf and both control units are on the top shelf. I measured the noise coming out of the speakers at full volume with my Radio Shack SPL. Tweeter 54 dB and midrange 65 dB before the switch. After the switch the noise at the tweeter was 61 dB and midrange 72 dB. So clearly the switch was bad with the power supplies under the control units even though they were on different shelves. The noise was 7 dB or so lower with the power supplies off to the side on the same shelf and not beneath on a lower shelf.
See system photo of rack for details. So, I agree with Downunder that these units are sensitive to location and distance from the power supplies. At normal listening levels, I hear no noise at the listening seat and almost none at the speaker drivers.