I am still intrigued by R2R and NOS. But sure convinced ( thank you Amirm) not to spring for a Bifrost. Doing a bit of a market survey and I find the vast majority have tubes in them. I assume the output buffer. Don't think they would be a very good IV stage. Now, a well done tube is a very linear device, but this still has the smell of a fad selling two buzz words for one. An excuse to double the price? Not quite like the fad for balanced lines everywhere. They do have their use, but I would bet 99% of them sold to consumers are because the salesman/slick page said so. Not because of long runs, ground loops, or high ambient RF. How much do I want to spend to get a -135 dB noise floor over a -130 dB? I would say my old dog cares, but poor guy is deaf.