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
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