Looking forward to seeing where you go with this Anthony – should be interesting.
I thought I'd share some of my thoughts on this approach as I keep coming up against hurdles every time I've considered building one of these.
If I could build one to fit my system and needs, it would end up pretty expensive, and considering what it would replace, I'd need to hear what it can do before committing. I know several here who's ears I've come to trust rave about them, but I haven't tried a TVC. My experience with simple level pots has not been good and I actually find things sound better without them (along with a
good pre-amp). I built fancy Alps pots into my 2A3 amp and even tried them in hot-rod shunt-bypass mode to see where this 'less is more' approach could go – and they are now out of circuit and just fill the top plate holes. Simpler amp circuit on a good active pre-amp sounds better to me.
I also tried stepped attenuaters of various flavors including a very nice DACT CT2 24 postilion. I had a problem with the 'steps' and even if you could use all 24 positions in your listening range (I couldn't), I sometimes felt it was just too quiet or too loud. Even when this was not an issue though, I still found a good pre-amp had more drive, dynamic contrasts and just balls (I'll call it...); the attenuator was super clean, detailed and airy, very 'hifi', but I liked listening to music better with the pre-amp.
I keep harping on good pre-amp because that's a big factor for me; I spent many years on the pre-amp merry-go-round before settling in on the Joule Electra I use. I kind of lost count of how many but I owned, borrowed, or demoed many tube, SS and hybrids over a 15yr period and lived with them in my system before settling on the one I now consider my end-game – haven't touched it in about a decade.
If I could somehow hear a TVC and thought yup, I gotta have one, the usability issues I'd have to contend with would be;
As many 'steps' as possible and hopefully, they are all mostly usable in my listening range.
I never thought much about a 'balance' control but do adjust it sometimes – I'd miss this but could probably live without it.
I need multiple inputs – currently have 4, use them all and sometimes would like more.
I need multiple line-outs – 1 to connect my main amp/speakers un-molested and 1 to connect the active/eq'd/SS bass fill pieces. Actually I'd like to have 3 – I have a headphone amp I'd like to connect without unplugging something else.
Remote volume control – never thought this was a big deal but now that I have it, I love it and wouldn't want to do without anymore.
So a tough leap for me; would it be 'better' (back on the merry-go-round I got SO tired of), could I get the functionality I'd like and could I actually build and afford what I'd be happy with? Maybe you'll convince me.