the wonderful human @zerodeefex loaned me the BF2 initially, @Hands has already done the nice long impressions above, keeping my typing shorter. so: 1. didn't have any SPDIF sources or converter, so will stay on the Unison train as it's clear, concise and convenient. sure maybe streamers with LPS are still slightly better in some TOTL rigs. 2. said it elsewhere, had one initially bought a BF2 + SW51, there's no sense spending $ on another DAC + Amp pairing for years unless moving way up TOTL tube amps. 3. Bifrost 2 is like a baby Yggdrasil A2. the areas it differs: reduced depth of stage but still good layering and separation. not quite as wide on the L R pans, and while the bass tone is Yggdrasil-like, there's a step less punch to the energy. but gawd, for the price- beyond stellar sound. 4. If the Bifrost 2 SE outputs are improved, well it's weird that I preferred the Yggdrasil SE into the SW51 amp. maybe for the reasons listed above more so than a transport/cabling difference. or maybe I can't pick out SE haze for better or for worse. should be a Golden Schlong nominee for price / performance ratio.