I've owned numerous vintage tube tuners over the years, including two different Marantz 10Bs, a 1954 REL Precedent (as you probably realize, that's Radio Engineering Laboratories, no relation to the modern British subwoofer manufacturer), a McIntosh MR71, and several made by H. H. Scott and Fisher. Among more modern solid state designs I've only owned a Carver TX-11 and a Kenwood receiver, both during the 1980s.
By far the most sensitive of these were the 10Bs and the REL Precedent, which were similar to each other in that respect. Despite the Carver's unique sensitivity-enhancing circuitry its sensitivity was easily bested by those two. The best sound quality of all of the tuners I've owned was provided by the REL Precedent, which I used in conjunction with vintage tube-based "multiplex adapters" made by H. H. Scott (model 335 or LM35) and Fisher (model MPX100). (The REL is mono by itself, but it provides a multiplex output from which these adapters can decode the stereo).
Unfortunately, of course, both the 10B and the REL go for multi-thousands of dollars these days, at least if in good condition. In terms of value per dollar the best in my experience was an H. H. Scott 310D used in conjunction with one of the multiplex adapters.
It goes without saying, of course, that condition can make all the difference with any of these older pieces.
Best regards,
-- Al
