motorized or unmotorized pots are noisey and cause sound quality issues and wear out ... i really dislike them. this wouldnt be a great way to add a remote function for volume.
digitally controlled (by rotary encoder) relay-controlled resistor-based attenuators can be made to offer 0.5db steps easily with a small number of relays, and these systems adapt well to remotes.
im integrating one into a balanced preamp im building for myself from one of passlabs designs.
im not even sure it would cost much more than a top quality motor-pot. the required components are cheap, but i realise they are labour intensive to design and build - which escalates price rapidly.. it would make sense if the bha was actually designed to have preamp functionality, but the pre-outs are in no mans land.. where it seems they have limited use.
the bha "preamp feature" is somewhat misleading ive found....
the gain of the amp is too high for preamp use and theres no switch to ground/mute the pre-outs in headphone use, or vice-versa. it needs a lower gain setting (like around 5 to 10 db gain) for preamp use and for use with sensitive headphones.
the volume knob is operated at the lowest end where theres a lot of channel imbalance and volume attenuation is overly sharp.
the bha volume control is ...not good
i was looking forward to using my bha as a preamp too until i received mine and realized this pre-out feature wasnt ideal/well thought out... a few small design mods would make it functional, but for some reason bryston doesnt seem interested in doing so today.. so i started building my own preamp... which ive discovered isnt half as difficult (provided a good design is available( as id previously thought.
Relay volume controls are great if executed properly but unfortunately, most of them aren't. The resistors have to be matched within very close tolerance of resistance and they must be good quality otherwise every benefit of such a system would be nullified quickly.
I have found these systems to be unreliable sometimes, especially if they are placed near sources of direct heat dissipation. So they won't work that well in tube amplifiers for example. I doubt Bryston will ever implement this because they've worked with taper atternuators for years and they do get it right amd it lasts.