Even now with the Kef’s i rarely go past 9 o’clock position. Sometimes maybe 10 when I’m listening to vinyl.
That’s definitely a problem, if you want to continue to use the Brio-r with one of the high sensitivity speakers that have been discussed. Stereophile measured the sensitivity of the LS50 as being 84.5 db at 1 meter for an input of 2.83 volts (the spec being 85 db). Roughly speaking the choices that have been discussed are about 14 db more sensitive than that.
Although
this photo shows the front panel of a passive preamp I believe the dial markings for the volume control are reasonably representative of the characteristics of rotary volume controls that are typically used in active preamps and integrated amps, in terms of db of attenuation vs. position. As you can see the 9 o’clock position corresponds to about 37 db, so with speakers that are 14 db more sensitive the listening volume you presently hear at the 9 o’clock position would be produced at a setting of about 51 db, not far from the bottom of the range. And as you can see, near the bottom of the range adjustment resolution becomes much coarser than at higher settings (6 db per marking increment vs. 2 db at higher settings); channel imbalances may occur, depending on the particular control; and as Auxinput pointed out earlier the amp may simply not sound as good.
Assuming your sources don’t provide a volume or output level control the one solution that occurs to me if you were to use the Brio-r with one of these high sensitivity speakers would be to insert a pair of
Rothwell attenuators into each of the pairs of input jacks of the Brio that you are using. Probably the 20 db version of the attenuator for the digital source(s), and the 15 db version for vinyl.
BTW, generally speaking I would recommend against in-line attenuators made by manufacturers other than Rothwell, as some of them have input impedances that are too low to be suitable for use with many source components. That will rarely if ever be a problem with the Rothwells.
Good luck. Regards,
-- Al