tvc vs avc

from a practical standpoint, what is the difference between a transformer vs autoformer based passive volume control? Bent Audio has moved to Slagle autoformers to replace the unavailable tx 103 S&B transformers, and apparently thinks they work at least as well.
I had John's wonderful Tap linestage, which used S&B transformers as you mentioned, and then went on to another great linestage, the Flora, that used autotransformers in its volume control. So, to answer your question either device used and set up correctly offers great sonic performance and from a practical veiwpoint are the same.
I did a DIY project using S&B 102 mk3's. I wired it in as an TVC switchable to AVC at first. Completely accidental, it was supposed to be a HT bypass. Scratched a few hairs out that day. Anyhow, I didn't notice much difference, just a bit more bass and gain with AVC. I have other options in bass control but even if I hadn't, the benefit of balanced connection and conversion with TVC was more important to me. AVC's can be balanced too, but it takes 4 of them. With different brands of either, there is not a direct comparison between TVC and AVC. These are also so system dependant that one man's molehill could be another's mountain.
Interested in knowing if some of you have had the chance to compare since the last post. I tried the Bent Tap-x before with the AVC and liked it better than an S&B passive I tried, but it wasn't a Bent NOH or TAP. Would appreciate additonal comments on the the TVC AVC differences. Hi Teajay - yup, still trying new stuff.
bump, any new obeservations?
Has the passive pre hysteria gone away? Are we all back to our glowing tube preamps?
Well for what it is worth I bought a Berning Micro ZOTL to use as a headphone amp. As luck would have it the one I bought could also be used as a line stage preamp, as well as a 1 watt amp.

I've been using it as a preamp for a month or so now, alternating between my other passive preamps. I still prefer passives and will be getting another one that is balanced, but this Berning has really made a nice difference in my system.

I hope to be getting my custom EL-84 amp this week and will be setting up a second system with the Berning and a pair of Tonian Lab TL-D1 speakers I just purchased. Source will be a Kenwood KT-8300 analog FM Tuner to start, then a computer audio set up when I get around to acquiring the components.
Custom EL84, not RM?
Correct, I love the RM-10 and just saw one pop up here. Was very tempted. This amp was built by Audiogon member Dertubemeister.