Thanks to all
Hooked it up to the Dennon transmitter, stereo preamp in R channel and Helix in L channel. Strange volume things happened when playing the guitar.
Changed the Denon transmitter to Mono -- things worked perfectly. Guitar and mono turntable output to both speakers with good sound quality!
Simple preset from scratch with clean tone was easily Adjustable to sound close to clean amp. Have not tried to optimize overdrive or stereo input to transmitter, but so far this is a really amazing unexpected benefit to the Helix.
Can't comment on the latency concern, as a newb it felt OK, but better players might find something noticeably annoying.
Again, thanks to all
Noledoc