Ayre V-Kxe and Thiel 2.4s

Anyone heard this combo?

I've been waiting for an appropriately priced Pass Labs 250.5 to pop up, but the wait has made me consider some other alternatives. In my conversations with Pass, they've steered me away from lower power options (e.g., the 150.5), so I'm concerned that the V-Kxe won't have enough power to really push the Thiels. However in reading over the positive Stereophile review of the 2.4s, I think much of the listening was done on the this amp. It does save me quite a bit of cash over the Pass 250.5 though.

Any opinions are welcome (along with other amp suggestions). Thanks folks.
At 150 wpc into 8 Ohms and 300 wpc into 4 Ohms the V5ke is going to power the 2.4s just fine. I use a 45 wpc CJ CAV50 with the 2.4s and have plenty of power.
Stevecham, with all due respect, he's already unsatisfied with much more power than your currently running with Thiel 2.4's. IMO, it might be enough, then again it might not. Depends the room, and the expectations.
Cal3713, may we ask how much do you comfortably want to spend on amplification?
I'm willing to spend up to $4000 (on agon)... just trying to explore the options and figure out which of those might be worth "auditioning" (i.e., purchasing used and reselling if they don't compare favorably to my current XA-30.5/INT-30A). I'm going to keep it and use its preamp so I can get a good A/B comparison. Getting a cheaper option is simply attractive because it opens up the cash for some other audio purchases... hence the flirtation with the Aleph 2s and the Ayre V-5xe. I'm in Boulder, I wish Ayre would just let me borrow one for audition (I checked and they won't... despite not having any CO dealers).
Stevecham, as Unsound pointed out I do find it surprising that you're getting enough out of the CJ. I'm certainly not in a big room (or a small one for that matter), but my current Pass (the INT-30A... which gives 60 W of class A power into 4 ohms, and probably tops out around 200 wpc) just doesn't control the lower end of the 2.4s. Bass is just all over the place, sometimes it shakes the windows, other times there's just nothing there even when it clearly should be. With the same amp, my Thiel 1.6s actually produced more bass on a couple tracks that I sampled.
Nope, haven't started to look through the options to learn their lineup yet... but I'll take a look. Any particular models you're a fan of? At one point I was considering Mark Levinson, but the reliability complaints and all the posts about getting the caps replaced turned me off.
Based upon some comments posted here on Audiogon, the cost of refurbishing Krells can be quite expensive, with that it mind, it might be best not to purchase anything too old, unless it has documented proof of already being appropriately refurbished.
Guys, next time you plan to be in Eugene, OR, please let me know so that you can stop by to hear my system. That's the only way I can convince you that I have plenty of power with the CJ into the 2.4s. And my room is not small; it has a high ceiling.
Stevecahm, I've heard an older similarly powered cj tube amp running older 2 series Thiels that were a much, much easier load, and while it could make sounds, those Thiels never could produce all they were capable of with that amplification.
The Pass INT-30A certainly makes absolutely stunning music on the Thiels... but only with certain types of content.
Ayre makes very fine gear....to get the most from it you should run it balanced
I find you experience interesting with the CJ amplifier.How good is the quality and control of the bass driving the Thiel woofer? what type of music? Is it possible The CJ handles the thiel better than a SS Pass amplifier? Strange things can happen within audio systems sometimes. Could the CJ actually have a better power supply and/or transformers?
As Atkinson noted in his technical review of the CAV50, "On the test bench, the Conrad-Johnson CAV50 delivered a just-to-spec 53Wpc into 8 ohms (17.2dBW) for 1% distortion, midband. Loaded down to 4 ohms, it measured 78Wpc (15.9dBW) single-channel, showing a respectable load tolerance for a tube amplifier. The output rating fell 1dB with both channels driven (eg, to 16dBW, 40Wpc, at 1kHz). At low frequencies (20Hz) the amplifier clipped at 36W (15.6dBW) (which isn't bad), and raised 65W at this frequency into 4 ohms (15.1dBW). At the other end of the audio band, the amp delivered a true 56Wpc at 20kHz into 4 ohms at 1% THD, with 45W available into 8 ohms (16.5dBW). This is a good result, confirming low shunt losses in the output transformer." I have had audiophile friends both of the tube and solid state culture, listen to this system and they all are impressed by the results. I get decent bass response, not up the level of my Krell/Thiel CS6 system, but convincing enough, and the notes are felt as well as heard. Incredible midrange and high end. I think it's the power supply and the output trannies that make this amp a gem.
Apologies; it was Martin Colloms, not John Atkinson who made those measurements.

Bottom line is that more power does not necessarily translate into improved sound with the 2.4s. I failed to mention earlier that I have also owned Musical Fidelity's 250 wpc, Krell's 150 wpc and CJ CA200 185 wpc integrated amps with these same speakers and, by far, and to my ears, the CAV50 outperforms the other sonically with these same speakers. It simply provides that "ahhhh" factor much better than any of the others; I know I was hoping that either the CJ CA200 or the Krell integrated would be preffered, but such is not the case. What I also know is that the 2.4s are nowhere as diffcult to drive as Thiel's older models, such as my 6s, which I power with a Krell 400cx. The 2.4s are highly, and I emphasize, highly, revealing of the quality of the power feeding them.
With all due repect, and despite the included commentary in those test results, those measurements aren't exactly impressive; clipped at 36W (15.6dBW) ("isn't bad", really ?), and well below Thiels recommendation. If anything, perhaps it's the power supply and output trannies that make this amp perform so poorly on the bench?
Here is Stereophile's measurements of the the Thiel CS 2.4s:
I think it fair to say, that it doesn't appear to be that easy a load for a typical low powered tube amp.
Hi Unsound,
It would seem(once again) that actual performance and listening in one`s system is far more meaningful than speculation based on measurements. Steve has actually compared the CJ amp to'3' more powerful SS amplifiers and the CJ sounds better(is`nt that the point of audio gear). Regardless of what'should' be the result based on amp power and supposed speaker requirements. What is there to debate or question other than your own personal belief that the 50 watt tube CJ should`nt outperform the bigger SS amplifiers. Should steve disregard what he`s heard in his own system? Why question his real life results?
This commentary regarding power supplies made me start wondering about my house's (rather poor) electrical situation. I'm in a short term (2 year) rental of a house built around 1940 and much of the house is on the same circuit as my electronics (and will actually blow if my girlfriend uses a hair drier or electric heater while I'm watching TV or listening to music). Given the temporary nature of the situation, I don't think I can run an independent 20 amp line, but is there a way to check whether that circuit is impacting the amp's current draw (and therefor my system's bass response)? Aside from having noisy power, my uninformed opinion was that current delivery wouldn't be a problem unless the fuse was breaking when I tried to play music loud (which has never happened).
I've never understood the argument of using the efficiency rating of a loudspeaker insofar as determining power requirements for an amplifier. I'm beginning to wonder if there is more to the equation. I'm currently using the V-5xe with Hales T8's which run at 87db and have nominal impedance of 4 ohms. I've been told by experts (someone who actually sold them) that the speaker needs enormous amounts of power. With the V-5xe I have never turned the preamp volume setting past 9 o'clock. With a threshold amp (which had the same power rating), anything past 8' o'clock would shatter window panes and my ear drums.
Charles1dad, I can't and won't discount Stevecham's listening experience, but he's the one that first provided measurements to support his position. I respect that he also offered this objective argument to his position. After all, without it; it all just becomes unsubstantiated opinion. That is not to say that subjective opinion is not without merit, and that includes his as well. Bear in mind, that I also offered similar subjective opinion with similar, if not quite identical gear. Furthermore, the OP's experience has suggested that under-powering these particular speakers was less than satisfactory. FWIW, based upon the posts here on Audiogon most seem to agree with Thiel, the OP, the usual technical arguments and my experience too, rather than Stevecham's.. If Stevecham is happy with his rig, power to him, but the OP is seeking advice and I opt to provide mine too. Speaking of which, what are you providing?
The obvious point is steve`s CJ amp drove ithe Thiel and the OP`s Pass amp apparently struggles. Among other choices perhaps he may want to at least considerThe CJ amp or something very similar based on steve`s great sonic result.
Charles1dad, the last line of my last post was uncalled for. Please accept my apologies.
It's a funny world out there... wish we could all just take disks/equipment over to each other's house to examine the true state of affairs. Even since I made this thread, my INT-30A has kept improving (I'm about a month into ownership but leave it on constantly), and it is simply jaw-dropping spectacular a lot of the time. I'm growing increasingly concerned that the only thing I'll like better on the next amp will be the bass control and I'll only notice that when I listen to the very specific types of music that the deficiencies noticeable.
Unsound, sorry, but can you elaborate on how knowing that the Pass is a 15 amp draw will help me?
Unsound I certainly accept your apology, no problems.

Cal I`m glad you`re getting more out of your current Pass amp.Sometimes more power is the answer, but often I find it`s not the core problem. It`s usally higher 'quality' that`s needed.
Russellrcncom, the placement of the volume knob might not be meaningful with re: to the respective differences between power output of the different amplifiers. The amplifiers just might have different input sensitivities for full power output, and your preamps might be providing that much or more or less than that much output at a given setting to drive your amplifier to full or near full output at less than the preamps full output. For example: one amp might need 2 volts to achieve full power output, the other amp might need 2.2 volts to achieve full power output to achieve full power output, while your pre amplifier might be able to put out up to 7 volts at it's maximum setting, and up to 2 volts at it's 8 o'clock setting.
Charles1dad, we don't know of Steve's great sonic results, only of his opinion of such. Thiel recommends more power, Pass recommends more power, and there hasn't been anything but an anecdotal reason to suggest otherwise. The measurements provided by Steve don't seem to suggest that the c-j or something very similar, would be as good, never mind better than what the OP has already tried. I would think that the point OP started this thread was to expedite the process of selecting the appropriate amp for his needs. With that in mind, I think it fair to point out that the c-j or something very similar, for the reasons I've already posted, is not as likely to satisfy the OP to that end as much as some other alternatives.
Cal3713, I was just responding to your thoughts of adding an independent 20 amp line for your amp.
Getting past discussions of how much power the Thiels would need...there's also the difference in sonics of the different amps.

Does anybody have experience hearing Pass XA series, Pass X series, and Ayre amps...preferably with Thiel speakers? That info is of more use to the OP than discussions as to how much power he needs...once he has an idea of the different lines' sonics, then it's a matter of choosing the appropriate power for his speakers.

I've heard Thiel speakers, and I've heard (and owned) Ayre amps. I suspect they'd work together reasonably well - but I wasn't a huge fan of the combo of Simaudio electronics with Thiel speakers - the combo was a bit edgy. Thiel speakers can sound a bit bright with electronics that are "modern" sounding - as such, I'd be looking for an amp that doesn't overdo the top end at the expense of the midrange. My guess is that, sonically, the Pass XA series would be better than the Pass X-series or the Ayre with Thiel speakers...so perhaps just moving up to a bigger XA-series amp is a good idea.
Countingbackwards, the XA30.5's the OP was using is a pretty modern design. Moving up to a more powerful XA.5 would probably be ideal, but there are budget considerations.
Any of the newer Coda amps would do a fine job with this speaker. All double down to 4 ohms and most are even 1 ohm stable. Most might recall a couple were specifically designed to drive low impedance panels and Coda OEM for Innersound/Sanders sound. Thats were I'd look.
Good Luck
Yeah, I wish I could go higher in the XA line. The 60.5s are kind of in the zone, although even getting the funds for that purchase would require living with the 30.5 for a couple more years. Although Renohifi suggested that that could be a solution, Pass themselves recommended the XA100.5, followed by the 350.5, and then the 250.5 as the best matches for the Thiels.
Interesting thread. Further thoughts are that, of the three much higher powered integrateds I owned for a time in this system, the CJ CA200 was the most enjoyable. What I missed though was the upper bass warmth of the CAV50; this is my second one, I too "second, third and fourth guessed" myself and finally returned to this model. Certainly that amp could drive the Thiels to much higher levels and not venture into tube glare territory. But i can get this system up to 95 dB with most music before glare sets in and that is more than I normally listen at for extended periods (I mean, how high do you guys expect to be able to go?). Fortunately I was able to find another on the 'gon and once this was back in the system, all sounded "just right" once again. I used to be very critical of the ear vs. technical issue, reading the literature on this, the Absolute Sound vs. Sterophile battles, etc., and, for a period of ten years or so, was convinced that measured specs were perfectly predictive of sonic performance. I have now at least partially moved over to the other camp in that there are component combinations that empirically defy technical predictability. Believe me, my expectations used to be more closely aligned to most of the sentiment expressed above with regard to the need to high current and Thiels.

I also have CS6s and when I was trading up from Bryston 7B monoblocks ten years ago, I first purchased a Krell 300cx amp; it was OK but I decided to try the 400cx the next day, so I took back the 300cx and traded up (full credit within 24 hours, blah blah) . The rssults were clearly heard. The more powerful Krell made a distinct improvement in dynamic swing and width and depth of staging. Bass was also improved. So there was my conclusion that high current amps are de riguer with Thiels. Until the CAV50 appeared, that is.

I really do wish you guys could hear this set up, at the very least it would make for some interesting conversation. If I hadn't "validated' it with others I trust, I wouldn't be so promotional about this. Remember it's that first watt or two that we most often listen to to drive our speakers to 80-90 dB levels in he listening position, and I can only conclude that in this case it is the quality of those first couple of watts that make the difference. I'm not using any NOS tubes either, but only low noise selected versions of JJs from tube depot.

I know this is somewhat arbitrary, but I think a system with high end aspirations should be capable of 100 dB peaks.
Hi Unsound,
I`d agree that is an arbitrary standard for sure. I sse no correlation with sound quality and volume level ability. Many systems can be built to play loud(quite loud) and yet sound rather poor. If someone has normal hearing ability and has put together a system that emphasizes natural sound with good resolution, 70-80db levels(on average) with peaks to low 90s is plenty for 'most'.

Again this is 'strictly' a personal decision and one must consider what levels are risky to their long term hearing.It seems the more a system`s resolution and noise floor are addressed/improved the more lively and involving it becomes at lower listening levels. This seems to lessen the need to crank it up in order to be satisfied.Of course YMMV.
Could be; I can certainly and easily get it well above 100 dB, the 95 is a nominal figure and I am sure that even on the rat shack meter, the actual peaks are 100+ dB.

High end aspirations...now there's an interesting concept.
Charles1dad, my post was a direct response to a question Stevecham asked in the previous posts. The ability to reach a certain volume level is no way the only, or the most important criterion. One can listen to such volume levels with some frequency, so long as the duration is not too long, without fear of hearing damage. Greater volume levels happen quite often during some live unamplified live musical performances. In that most of us listen in very different environments than live venues, not achieving actual potential live volume levels is probably not called for most us, but a reasonable proximity is not too much to ask for.
Unsound, I think we`re in agreement,determining reasonable proximity is subjective and as stated earlier an arbitrrary standard.
Interesting action over hear folks. Thanks for all the comments. I almost bought the last 250.5 that was on here, but it was in Canada and I didn't want to pay to import it... so I'm still considering the other options.
Stevecham, I suspect that with the Thiel CS 2.4's set up as the Thiel recommends, that at 100 dB the conrad-johnson CAV50 would be well into clipping.
Unsound, feel free to go ahead and invalidate my assertions and experiences. It's OK, this is common place in the world today. But is it based on experience or speculation?

There is no "well into clipping" going on here, and frankly, in this regard, you don't know what you're talking about. So while I appreciate your comments in your attempt to poo poo my CJ/Thiel rig from a non-listening distance, my sense is that this comment is one that is built on pure speculation and not on reality. But that's the luxury of the internet isn't it?
Maybe some of the differences in opinions are related to global negative feedback. I had the CJ LP140m which uses a small amount of feedback. Comparing to another 350W no feedback amp that I have, the CJ had tighter bass control despite lower power rating. The macrodynamics of the CJ is compressed comparing to that of the 350 Watter.

I had both Thiel 2.4 and 1.6. The 1.6s are much easier load.
OK, The 2.4s measured 88 dB at 1 watt at 1 meter at 1% THD. The CJ at worst puts out 77 wpc into a nominal 4 Ohm load at 1%. So for most of my listening at 80 to 85 or so, I am using a watt or two.

Unless 1% THD is considered to be clipping...

Look, if it made a difference and improved things SONICALLY I would have GLADLY (yes I initially did the MATH experiment X 3!) kept one of the Musical Fidelity, Krell or CJ (solid sate) integrateds.

I'm done here as I feel I;ve been effective in gettign my points across;

Cal: the Thiel 2.4s are relatively easy to power, it's the quality of the power that makes the difference.
Stevecham, the Thiel 2.4's don't measure at 88 dB 1 Watt at 1 meter. They measure 88 dB 2.83V at 1 meter.
If my understanding is correct(?), if you take into the consideration the actual impedance of the speakers, you'll find that Thiel 2.4's are actually closer to a nominal 83 dB 1 Watt at 1 meter.


The 77 Watts wpc into 4 Ohms is what the cj CAV50 can do when only driving one channel. When driving both channels at 1 kHz the power drops to 40 wpc. It's interesting that the power output seems to go up into 20 Hz (a moot point, as that's below the Thiel CS 2.4's capabilities) and also go up at 20 KHz (which the Thiel CS 2.4's are capable of) for those that can hear that high up.


Keep in mind that the Thiel CS 2.4's do have a rather challenging phase angle too. Not something that most low powered tube amps tend to appreciate.