Pre-amp suggestions for Thiel 2.4/Pass Labs XA30.5

Cal3713...is the XA30.5 capable of driving the 2.4s without any problems? No tonal abberations or soundstage collapse at higher volumes?

In any case, as for preamp suggestions, when you say your CAP-151 is being outclassed, how so? What are you noticing that you would like to change (more tonal density/texture, more resolution, more PRaT, more bass articulation/heft...)? Just trying to understand what it is you are trying to change or improve upon to tailor recommendations. I am assuming you are willing to consider used as well. Thx

Cal3713...I would assume a used Pass XP-10 would be a good combination with your XA30.5 (check with folks at Reno Hifi who often have good used/demo inventory and I believe they allow 30-day in-home auditions). Other options to consider:

ARC LS-17: http://www.audiogon.com/cgi-bin/cls.pl?preatube&1328708163&/Audio-Research-LS-17-Tube-Prea. very detailed/resolving but still gives you smooth/continuous flow of music with 3D presentation

CJ Classic SE: http://www.audiogon.com/cgi-bin/cls.pl?preatube&1329081914&/conrad-johnson-Classic-SE-tube. Shoudl give you the CJ golden hue but with updated modern and highly resolved sound. SE version includes Teflon caps which take a very long time to burn in (>600hrs) but should deliver on resolution and spatiality in spades. This looks like a good deal for a brand new unit with full factory warranty.

Good luck.

Cal3713...the output impedance of the Aesthetix Calypso may present a problem in the treble region given the high impedance at 20KHz (3900 ohms vs. 30Kohms input impedance for your Pass amp via balanced, < 1:10 ratio). On paper, this suggests potential attenuation (or think of it as a roll-off) in high frequencies, so this may make the overall tonal balance more shifted towards the midrange and bass. If you are set on that option, I would highly recommend trying it in your rig before purchasing if you can.

You should check the ARC LS-17 for measurements as well. If you cannot find output impedance curve, I would call ARC and ask them. Let them know what amp you have so that they can advise you on whether the LS-17 would be agood match from an impedance perspective.

Good luck.

Cal3713...thanks for the update. That was my concern in my post above. I have seen X350.5 often paired with the 2.4s to good effect. I am sure the X250.5 will give you plenty of power and current delivery to drive the Thiels with ease. Good luck with the journey and enjoy it.

Pubul57...Thiel has shown its speakers often with Bryston and Simaudio amplification at shows int he last 2-3 years. But again, as Unsound has pointed out, this could be more a function of local dealers, etc...I drive my 2.4s with ARC Ref 110 and love the combination. I am probably leaving a little bit of performance (dynamics and lw end extension) on the table but what I gain in terms of tone/timbre, separation, transparency/resolution, and 3D dimensionality is quite nice. I initially drove the 2.4s with Musical Fidelity's A5 integrated amp (250wpc into 8ohms and 500wpc into 4ohms) but the top end was a bit jarring and resulted in listener fatigue. I also tried out Simaudio P7/W7 (separates) and the i7 (integrated) for about a week each and liked the Simaudio/Thiel combo.

Not to suggest that good bass is the number one priority, but IME without good solid bass response the Thiels can sound a bit tipped up. I think the part of the appeal of the Thiels, is due to the outstanding balance of all paramaters, rather than any specific one.

Explains a lot of the stereotype, but also what some swear by Theil as among the best speakers ever made - got to have the right amp:)

Agree with both those statements. It's funny that with my 250wpc MF SS integrated amp, I found the top end harsh and the overall sound a bit thin, whereas with my 110wpc ARC tube amp, I have a much more natural and neutral tonal balance without any portion of the frequency spectrum thrust forward or recessed. I think the power supply in the ARC amp was clearly superior to that of MF.

Cal3713...if there is a way to audition the X250.5 before purchasing it (or maybe negotiating a time frame in which you can return the amp if it's not a good fit and just be out the shipping costs)?