Jeff Rowland Pre with Pass Labs X350.5 or X600.5

I think that the current Capri are Criterion are the pre-amps to consider for you Pass amps. Read Guidocorona's review of the Capri. Word of mouth has the Capri on equal footing or better with most of JRDG's prior efforts, as line stages. One of the prior pre-amps is noted for one of the best phono stages ever, unfortunately I forget which. The Capri's phono-stage, which is shared with my Continuum 500 intergrated, is very good.

The Criterion is the current no-holds-barred effort, with battery power (rechargeable). I haven't heard it yet, but if it's better than the Capri, then it's really something else.

Guido favorably compares the Capri with Power Factor Correction added to his ARC Ref 3. The interface with your Pass should not be any issue.

If you've got a line on used JRDG pre-amps, then the more recent models, as you reference, are probably the best bets. I haven't heard Jeff's very early designs, but many have written that they tended to be pretty warm sounding. (Not an advantage in my book).

Dave

Hi all, my apologies. . . I am not at all familiar with older pres from JRDG. . . but -- for what it matters -- I have reasonably good experience with the current JRDG Capri, which has been in my system for the last couple of months. I still contend that it is a magnificent device, although after several hundred hrs of breakin of Capri connected to the PC1 PFC unit, I am coming to the conclusion that I prefer it even better without PC1. . . greater extension, authority, staging, imaging, micro detail, macro/micro dynamics. My early Capri+PC1 findings were based on both devices rrelatively fresh from the factory, and my findings after break in appear to differ with my original ones. It is fair to remind that PC1 was designed for high current devices such as 102, 201, and 501 amps, not for low power devices like Capri. JRDG does not necessarily support use of PC1 on Capri. As for Capri matching Pass amps. . . Pass amps have an input impedance of 22K Ohms, while Capri has an output impedance of about 40Ohms in balanced mode. . . compatibility should be without problems. Pass and JRDG being balanced designs, I suggest connection of JRDG pres to Pass amps using XLR ICs.

I confirm that I originally preferred Capri over Ref 3. I will resume comparisons of Capri with my ARC Ref 3 in a couple of weeks, after I receive a set of 6H30DR NOS tubes.

And yes, Capri being this good, I am already fantasizing about the upcoming JRDG Criterion 2-box pre, which is expected to start shipping early in Q3.

Guido

Coherence II appears to have an output impedance of 50Ohms. See:
http://jeffrowland.com/ClassicSpecs.htm#Coherence
On the same page above, you will find Synergy II appears to have an output impedance 40Ohms unbalanced and 80Ohm balanced.
If input impedance of Pass amps ranges from 20KOhms to 30Kohms, compatibility with Coherence II and Synergy II is all but assured. G.